Hmm, "thread of the month/thread of the year" contest... all gonna be won by DC :'D
Also we have a radio, @Deftones did have a nice idea about using it.
Then again the problem of timezones still remain in this case but not as strongly as with gaming projects. Like, we usually have some half-dead "let's game together" threads, but I never had a chance to join one myself... might be my lack of effort though.
And well, challenges might be fun too. The ones where you do stuff and post a video on youtube. We even had something along those lines.