I've suggested a "Like" button on a semi-big forum, around 40.000 posts, but it was declined. I suggested to replace Reputation with Likes since I'd much rather say "Thank you", or "I like your post", than going over to his page, and give that specific user a reputation. Reputation causes nothing but drama, I wish big boards, especially MyBB forums would switch to Likes instead of the reputation system. There are lots, and lots of members who whine about negative reputation, or asks for it.
I think it was one of the best implementations that the site got so far, I really like that system, well done.