Atlas Press are a small(ish) publishing house that specialize in avant garde literature. If it's Oulipian, 'pataphysics, Dada or Expressionist these guys are likely to publish it. I first found out about them when I discovered George Perec and the OuLiPo, and through their books I discovered the wonderful world of "anti tradition". I have a fair few of their books all of which are really inspiring and challenging but The Oulipo Winter Journeys is such a lovely edition I thought I'd post a couple of picks.
Some of the authors they publish include: Georges Perec, Raymond Queneau, Alfred Jarry, André Breton, Harry Matthews, Unica Zürn, as well as the output from the College of 'pataphysics.
Atlas Press (http://www.atlaspress.co.uk), don't be put off by the poor quality site, the books are great.