Lol, I don't think anyone here is interested in tipping anyone else. With exceptions, of course. I did tip someone who gave me a tutorial on how to do a screen shot copy/paste thing, and I did so because he had his bitcoin addy in his profile.
It would be nice to have a tip bot, I think. I just don't think people here are going to give up their precious bitcoins. And most of the posting here is shit anyway.
To add onto that, I don't think the work required to implement a tipping function would be worth the usage it would see. People scarcely give out tips, unless they open up a bounty thread to have their question answered quickly.
I think theymos already chimed in on this topic a few months ago, and isn't interested in implementing this feature mainly because it would make the forum liable for any lost funds, which is understandable.