Something a really like is brainstorming about features that would make Ubuntu even more awesome. Even though we already have Brainstorm and there is a UDS twice a year, I think a monthly session with experts would be something very meaningful. Ideas get a lot better when you discuss them with a group.
I proposed two solutions at Brainstorm, and I like both.
Have a BoF session on IRC every month. People from all over the community can brainstorm the most daring things and if they like it, propose it at Brainstorm/start working on it/create a blueprint/propose it for the UDS. I think the whole community should be allowed to join, but there should at least be some experts there to comment on ideas.
Have a blog meme after every new release where you write about the things you miss in Ubuntu or the things you think that would make Ubuntua absolutely irresistible. This isn’t something that can be forces, it has to be done voluntarily by the community members.