I hear people always talking about critical mass in San Francisco, what is it, and when does it go on? Can anyone join? All bikes are welcome?

Are there any celebrations taking place I should know about?

So I'll be in San Francisco in the beginning of January of 2010. I'm wondering if there'll be special events going on there that are must do's or must see's? e.g. concerts, shows …

is there a good site that is well known to list tech meet-ups/events, so you can be aware of events that are coming up in the city? ie: Google IO, Macworld, Ruby talks. Or even …

people who move here have a hard time finding things to do, at least when it comes to the interesting events that go on. What are good websites for people to find events? What inf …