Also, since Chris raised the idea of us hosting Wikimania - personally I'm not sure what the benefits to WMUK of hosting would be - can someone spell them out?
Here are some benefits off the top of my head. I am sure there are more too, but these seem to be the most important:
Builds enthusiasm amongst local Wikimedia community both because of the planning process and the chance to easily, at low cost to them, go to the conference and learn about cool things other people are doing
Chance to showcase the chapter and its approach to stuff, because of the high number of in country attendees
Chance to invite partners to observe the amazingness (both in diversity and in variety of projects) of the global community
Chance to create media hype that might draw in people who had otherwise not participated in Wikimedia stuffs
Chance to get other Free Knowledge communities more engaged, or at least in better contact, with Wikimedia