I haven't really had any luck yet. I was a Farker back in the day, but went to Reddit while a lot of other people were going to Digg. Back then I loved Reddit as a social news site, but now I really dislike it because it's mostly a meme and image aggregator. (IMO it was the memes, image macros (Advice Animals) and meta references that killed that site.)

That said, I like PinkBike.com for MTB stuff and Hacker News for tech stuff. Those are really the only two forums where I actually leave comments these days.