I've been thinking about what it might mean to "push the envelope". The phrase comes from mathematics and was introduced into general usage by Tom Wolfe in his 1979 book about the space programme, The Right Stuff. It is used in engineering to describe an attempt to extend the limits of performance, going to extremes, taking something beyond its normal course. I guess that's why they chose it for the name of this section of the programme.

I looked it up in PC Magazine and discovered a related expression: "bleeding edge". A pun on "leading edge" (aren't they witty, those scientists), it implies that using the latest technology is often risky because it has not been tested with enough users and may not perform as expected. Introducing an advanced product or service is also risky because the user community may not be ready for it or really want it.

But these artists are all willing to take that risk. And that, in a way, is what Fringe is all about. Being ahead of the pack. Bringing an audience something they have never seen before. Driving right up against the edges of theatre, dance, music, comedy, performance and seeing what they might rub up against. Pushing the envelope so hard that the postman might have trouble fitting it in your letterbox.

At a lecture I attended by the actress Fiona Shaw last summer I asked what she thought was so special about live performance, what it could do that other media could not. "It can knock your socks off" she replied, and I think I know what she meant. There have been times when I've been at a live event, where I have felt that the performers are pushing at the boundaries of what I thought about art and life, and I'm feeling my socks knocked, and I know this is the real deal.

This year's Fringe programme will feature shows based on Stephen Hawking's teachings (I'm So Close It's Not Even Funny) and performers' real mothers on stage (The Show about The Show and Susan and Darren). People will fly to the moon on an inflatable mattress (Moonflight) and St Bono will provide divine inspiration (Eejit of Love).

I have been at performances which have come at the world from such a left field angle that I've laughed myself to pieces. I saw the work in progress of Priscilla Robinson's The Show about The Show earlier this year and felt her work was so unique and refreshing that I thought it actually might be good for your health to spend time at one of her performances.

There are companies and artists here who are smashing the boundaries between music, dance and theatre. John Moran's performances with Saori are like nothing you've ever seen, blending lip synching, split second synchronicity and spiky wit to extraordinary effect. Anyone who saw their show in 2006 will know what I mean, everyone else should see what you've been missing. This year they're bringing with them downtown New York rising star Joseph Keckler, who also presents his genre-bending double bill Human Jukebox and Cat Lady.

They're not the only performers blending music and performance in new and innovative ways. Volcano's Four Horsmen Project brings together perfomers, designers and animators from across Canada to explore the avant-garde sound poetry of 1970s innovators the Four Horsemen, using sound, breath and the human body. schindel killius dutschke's Moonflight features Beethoven's Moonlight Sonata and German folk song in an innovative musical look at space exploration. Eejit of Love is that rare and promising thing: a piece of new Irish musical theatre.

Composer Ian Wilson, choreographer Anne Gilpin, trumpeter Mark O'Keeffe and designer Conleth White collaborate to create an atmospheric multi-sensory immersive landscape in Tundra. Mute Comp's Grasping The Floor With The Back Of My Head blends high octane dance and visceral physical theatre with exhilarating live music.

We are familiar with Jo Strømgren's unique and idiosyncratic combination of physical rawness and humour from The Hospital and The Convent in past Fringes. This year's Polaroid is a snapshot of what's really going on around the North Pole. It was made with performers from Greenland and astonishingly was the first Greenlandic theatre performance in history to perform at the Royal Danish Theatre - even though Greenland has been a Danish colony for almost as long as the theatre has existed.

There are other shows which push the envelope in trying to find new ways to understand the world we live in. Ecole Jacques Lecoq graduates Theatre Why Not's I'm So Close It's Not Even Funny tries to make sense of what time is and why it matters to us. And one of the most acclaimed young companies in Europe at the moment, andcompany&Co., present Little Red, "a docu-tale of a past which could have been our future", a look at the failure of communist utopia from the vantage point of the 21st century. They combine a playful postmodern aesthetic with intense philosophical inquisitiveness, innovative light objects and electronic music with real stories of Europe's communist past. I've been looking forward to seeing this show for months and it will be a real breath of fresh air for Irish audiences and practitioners alike.

As will Susan and Darren. Quarantine are one of the most exciting, surprising and dynamic companies in Britain today. In their own words they "question accepted conventions of theatrical performance, and ignore boundaries between artforms... borrow and steal from visual art, live art, music and dance - and from real-life events, journeys, conversations, films, cooking, books and arguments." They have worked with young working class men, three generations of a Glaswegian family, and most recently a group of old people, children and animals (for a show called Old People, Children and Animals). This show will feature a dance workshop for the audience, a performance by a dancer and his real mother, and a buffet prepared by the audience.

I read a press release for Eric Davis and Ten Directions' Bouffon Glass Menajoree. "Imagine Borat parodying Tennessee Williams directed by John Waters. These deformed anti-clowns subversively make fun of everyone and everything. Why would ANYONE do this to an American masterpiece?"

Why the hell not, I say. Bring it on and let's see what happens. The last people to attempt such an outrage in the Fringe were a new company who tackled Streetcar back in 1996. They were called The Corn Exchange and look where they've ended up...

Tom Creed is a theatre director. He is Associate Director of Rough Magic, joint Artistic Director of Playgroup and Theatre Curator of Kilkenny Arts Festival. His production of Mimic by Raymond Scannell is presented as part of the Fringe.