there is the annual German Ubuntu Users Conference (if you dislike
Canonical: is is fully community driven), this year taking place in
Heidelberg in October . At Ubucon other Ubuntu flavors are highly
welcome (I say it as Kubuntu user).
In the past two years I have been giving talks and a workshop about
ownCloud. The ownCloud talks  have always been well-visited, the app
dev workshop not so much. However, I will probably not be able to attend
this year. Since it would be sad not to have a talk this year again,
maybe someone of you wants to propose a talk (or workshop or discussion).
 http://ubucon.de/2013 (German)
 CfP: http://ubucon.de/2013/cfp (German)
 last year`s:
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