Journalists are dabbling in it. Academics, historians and fashion designers are having a go. Even comedians and milliners are giving it a shot. So what is it that unites these disparate professions? Guest curating is the answer, and representatives from each of these professions have recently been given the chance to curate temporary exhibitions.

Artist Mark Wallinger, comedian Vic Reeves and milliner Stephen Jones are among those who will open shows that they have curated this year. But what does the organisation and the curator get out of this arrangement?

It's not unusual for academics to bring to bear their specialist knowledge on temporary exhibitions. It makes sense to get the experts in if a museum or gallery wants to draw out a particular story or explore a specific theme. And academics are often keen to see their research interests turned into something more tangible than just another lecture or journal paper.

Leslie Topp and Gemma Blackshaw are co-curating Madness and Modernity, which opens at the Wellcome Collection, London, in April. Both are academic art historians and when they met at a conference a few years ago, they realised that they had research interests in common.

Funding from the Arts and Humanities Research Council allowed them to work together looking at the relationship between psychiatry and architecture.

"We came up with so much material that we decided to put together a proposal for a show," says Blackshaw. "We had research that usually stays within the university or within the art-history community, but it's great to see this work being taken to a non-academic audience."

And although the process of requesting loans from private and public collections was time consuming it was worth it, says Topp. "Assembling the objects was almost like being a collector - I wasn't really prepared for how exciting, interesting and thought provoking that was."

James Peto, the senior curator at the Wellcome, worked with Blackshaw and Topp on the exhibition. He believes that it is essential to work with experts from outside the institution. "We almost always need help from outside. We couldn't do what we do here without them - it adds variety and challenges ways of thinking."

In some cases, where institutions are attached to a university, making use of the resources close to hand is logical. The Women's Library's 2006/07 show on prostitution was curated by Liz Kelly, the professor of sexualised violence at the London Metropolitan University, which runs the library.

Similarly, the recent Jack Kerouac exhibition at the Barber Institute of Fine Arts at the University of Birmingham was curated by Dick Ellis, the head of American and Canadian studies at the university.

It's not just temporary exhibitions that can benefit from external help. When staff at the Museum of London Docklands began to think about a permanent gallery dealing with slavery they soon realised that they required outside expertise. Tom Wareham, the curator of community and maritime histories at the museum, says they decided to bring in an external curator almost immediately.

"We realised that this particular subject might be difficult and sensitive and that we needed the academic and social knowledge that someone from outside could bring."

Wareham approached Caroline Bressey, a lecturer at University College London, whose main research area is black history in 19th-century London. She worked as part of the curatorial team throughout the project. "We would work on ideas, put together a collections list and then take that to consultative groups - the final say was based on discussion between both," Bressey says.

Both Wareham and Bressey agree that one of the main advantages of working in this way is that it brings fresh perspectives to the collections. "Like all curators, after a while you get tunnel vision. But working with others broadens your horizons, provided you are prepared to be flexible," says Wareham. "It can be a critical process, but that makes you more confident about what you present to the public."

Bressey agrees that the end results are better for having the input of different perspectives and specialist knowledge that the museum might not necessarily have had on the staff team.

There is also a long history of artists working with museum collections and curating shows. The Charms of Lincolnshire, the opening show at the Collection in Lincoln in 2006, was curated by Turner Prize-winning potter Grayson Perry, who also curated Unpopular Culture, an Arts Council Collection touring exhibition currently at Southampton City Art Gallery. For both exhibitions Perry researched the collections, selecting objects and art that suited his own personal themes.

In the summer, comedian Vic Reeves will curate an exhibition at Tunbridge Wells Museum and Art Gallery. Reeves might not seem an immediately obvious choice for a guest curator, but he is a local resident, amateur artist and a museum fan - he once set up one in his house complete with lots of objects and labels. The fact that he is a household name doesn't do any harm either.

When the Victoria and Albert Museum (V&A) wanted to put on an exhibition exploring its hat collection it approached milliner Stephen Jones. Although Jones has an international reputation, Oriole Cullen, the curator of fashion and textiles at the museum, says it wasn't the only reason for choosing him.

"He's an expert in his field, it's not purely a fame thing," she says. "He has an encyclopaedic knowledge of his subject, wonderful recall and references and a great relationship with the museum.

"Stephen has always been a big fan of the V&A," adds Cullen. "We've had talks with him over the years about doing a collaborative project. We thought it would be nice to have an exhibition that he came in and co-curated."

She says they wanted to show how the museum connected with the creative industries and how it is used as a resource by people who work in that sector. This is borne out by Jones, who recalls being encouraged to go to the V&A as a fashion student to seek inspiration from the collections.

"It was more than the actual objects, it was the whole world of museums. We rarely, if ever, drew the costumes; we were encouraged to focus on items as diverse as porcelain and glass and to incorporate these ideas into new forms of fashion design," says Jones in the book which accompanies the exhibition.

Jones was invited into the archive to research the exhibition. "He started looking at the hats in store and pulling out ones that spoke to him, photographing them and seeing what story fell into place," says Cullen. The resulting show, Hats: An Anthology, opens later this month.

In some cases, the external expertise might come in the form of an independent curator. James Hamilton has had a long career in museums and currently works part time as a curator at the University of Birmingham.

When he's not there, he devotes his time to freelance curating. His current show, Turner and Italy, is at the Palazzo dei Diamanti in Ferrara, Italy, after which it will tour to the National Gallery of Scotland, Edinburgh, and the Museum of Fine Arts, Budapest.

Hamilton says that no museum can have experts on everything - particularly in the current climate - and the advantage of a freelance curator is that they can be hired for a fixed price and do the job efficiently and to deadline.

"They know how much it will cost - it's a set fee - and they know, within the limits of human frailty, that the person has a track record and will deliver."

He is enthusiastic about the freedom and creativity of the process. "I have a free hand to plan the shows, within realistic limits of loans that are available," he says. "I've never known or asked what the budget is for loans. I say: 'I'd like this and this and this' and they take a deep breath."

Journalist Joanna Moorhead is co-curating Surreal Friends, an exhibition at Chichester's Pallant House Gallery in 2010. She says it is energising to work with people from a different sector.

"When you do a job that isn't your own day job there's always a sense of being almost on holiday - because it's not your real world, it's not the world that has become mundane to you. In that sense it's a rather exotic environment and you don't quite get over that in the months - or in my case, years - that it takes you to curate your show."

But while there are advantages on both sides of the relationship, there are also pitfalls to be aware of. Moorhead complains that the process can be stressful and confusing to an outsider, a gripe that is echoed by others who have ventured into curating. Nearly all describe it as a steep learning curve from both an individual and institutional point of view.

And although the process can be rewarding creatively for guest curators, it's rarely that appealing from a financial point of view. One described the fee they received for pulling together a show at a regional gallery as "miniscule" and many say that the payment is not commensurate with the amount of time and effort that goes into creating a show.

The real driving force seems to be a passion about the subject matter: "It has to be something you believe in order to sustain the momentum," says Topp. And then there is the ultimate satisfaction of seeing the finished product. "It's always an emotional moment when you first see the show," admits Hamilton. But he stresses that you won't get that pay off unless you work together.

"It's a performance. It's like being the conductor of an orchestra. The curator and the gallery have to work together to create a wow for the audience."

Guest-curated exhibitions this year

The Russian Linesman

Curated by artist Mark Wallinger
Hayward Gallery, London, 18 February-4 May (then tours to Leeds Art Gallery, 16 May-28 June, and the Glynn Vivian Art Gallery, Swansea, 18 July-20 September)

Hats: an Anthology

Curated by milliner Stephen Jones
Victoria and Albert Museum, London, 24 February-31 May

Turner and Italy

Curated by University of Birmingham curator James Hamilton
National Gallery of Scotland, Edinburgh, 27 March-7 June

Madness and Modernity

Curated by art historians Gemma Blackshaw and Leslie Topp
The Wellcome Collection, London, 1 April-28 June

Henry VIII: Man and Monarch

Curated by historian and broadcaster David Starkey
British Library, London, 23 April-6 September

Handel Reveal'd

Curated by conductor, musicologist and Handel biographer Christopher Hogwood
Handel House Museum, London, 8 April-25 October

Tunbridge Wells Museum and Art Gallery

An exhibition curated by comedian Vic Reeves
4 July-29 August