Ther Wikimania Writing and Media competition, in various categories. Originally, this was limited to content created in the past year, but that led to various problems with defining what that meant, and people misunderstanding the stricture; so now the contest is open to all wikimedia content.
http://meta.wikimedia.org/wiki/Wikimania:Competitions
Prizes include O'Reilly books and Wikipedia swag in German and English, rare pieces of currency, and probably some Xiph.org swag as well. Suggestions for special contest categories are welcome.
Currently, we have only one video up for the video prize -- which I guarantee will be something sweet. So if you have any good video to upload, upload it now! (Or send it to me via mail; it can be in any format; NullC and I will handle re-encoding it for you.)
Finally, Bdk and I are looking for judges to help judge the submissions.
I. Nominate people you think would make good contest judges here: http://meta.wikimedia.org/wiki/Talk:Wikimania:Competitions II. A few people suggested the idea of having known writers and artists, not necessarily Wikimedians, be on a celebrity panel for the final judging. Suggest people you'd like to see on such a panel as well. (also on the above page)
Cheers, SJ