I have become addicted to qna.live.com, which is Windows Live's community question answering application, which has been up for a couple of months.  While it seems like a lot of the questions are either lame ("WHAT DO YOU THINK IS THE BEST COLOR FOR A CAR") or unanswerable ("Why do you think my cat doesn't like me anymore"), there are some good ones.  I try to answer at least one question a day, and I generally only answer ones that I have at least some clue on.  My rules are:

 - avoid political questions, unless they are strictly fact based.  For example, I would answer a question "How many congressmen are in the US House of Representatives", but I wouldn't answer "Why is George W. Bush such an ass?" (I wouldn't answer "Why is Hilary Clinton such an ass?" either).

- never answer opinion questions...because who really cares what my favorite season is?

- back everything up with evidence (or a wikipedia link, which is sort of like evidence)

- Don't contribute unless you have something to say.

The way qna works is that you get points for answering questions, more points if your answer is judged "Best", and points for voting on best answers.  I have been answering questions for a while, and today went over 1000 points, which makes me "level 3".  You also get points for asking questions, but I haven't come up with something interesting to ask yet.

There is also "reputation", which is a rating from 0 to 5 stars, which seems to be based on the % of your answers that are judged "best".  I usually go between 2 and 3 stars. One frustrating thing is that if I have 3 stars in my reputation, and I start answering more questions, I lose part of my 3d star.  That makes me hesitate before I answer things.

It seems like most of the questions I answer are technology or programming related...I like answering the history type questions too, but most of those seem to be invitations to a flame war.  You know what they say about arguing on the internet.

The questions I have answered are here.   (and if you want to start answering questions, just ask for an invite, I have a few)