Karma for posting is a horrible idea--it encourages people to post for no contribution. Tracking 'thumbs' might be a good idea, but even then I wouldn't be keen on making it very prominent. Just on your homepage a little score for you to see how many people like your stuff would be fine. (And on people's infopages, I suppose. No need for it on every post, though.)

I also like stack-style replies for technical or otherwise questioning threads, complete with rewards for being useful.

If people want to chat with other pinsiders, they should do so in the OT area. I'd support wholesale moving of posts to a 'chit chat' thread when topics are derailed. Posts like "oh hey, how are you doing" do not_ belong on a topical thread on a public forum.

I would also support auto-hiding posts with a certain number of thumbsdown.

Regarding "abuse" of thumbs: it basically doesn't happen for thumbs up, given my experience on other fora. It's very hard to "abuse" such a thing, anyhow.

It's also a really good idea to encourage people to use them rather than post useless "yep" posts, and gets less talkative people (like me) to feel more invested, because they can participate without having to post. I'd also like to see the interface more streamlined, the giant box that pops up when you thumb something is super annoying.

Thumbs down, or similar, are often a terrible thing, as you get vicious cycles of people down-thumbing each other, as pointed out above. A more-liberal definition for the tilt warning is probably the way to go, and then have the mods keep an eye out to make sure people aren't tilting at windmills.

As an example of a site that uses a system similar to this one, check out boardgamegeek.com: clean, simple interface, with thumbs and 'hide this post' options. (You can hide a post just for you, or flag it to be hidden by everyone.) Yes, some people 'whore' thumbs, so keep them on the profile for people to feel good about themselves, not on each post to make things into a contest.

(BGG's a much, much busier forum than pinside, and their front page is cluttered because of it. Click through to any random topic to see the interface I'm talking about.)

I had thought I had said exactly this, but apparently didn't do so very effectively. Thank you.