BiFest is a one-day event celebrating bisexuality, for bisexuals and bi-friendly people. Originating in London, it has now spread to several other UK locations.
Oxford BiFest will be on 27 March 2010 at the Oxford University Club; see oxford.bifest.org for details.
The first Welsh BiFest will be in Cardiff, on 24 April. See here for details.
Brighton BiFest happened on 7 March 2009. Details of that event are at brighton.bifest.org. There may be another next year, but no definite plans.
Manchester BiFest happened on 3 October 2009. Another is tentatively planned for 2010 - see manchester.bifest.org for details.
Birmingham BiFest happened on 21 November 2009. There may be another one next year; see brum.bifest.org for details.
London BiFest happened on 16 May 2009. There are currently no plans for one in 2010 - although London will be hosting BiCon - but there may be one the year after: london.bifest.org will have details when they're available.