Lauda,
I see how one could abuse this system. Sure, you can make a thousand QS alts and use them to "like" the heck out of a post, but to what end? There is no benefit, no bonus for having many likes. If someone wants to spend hours logging in and liking posts, let them.
Well, as an example newbies could get tricked into believing false information (since they're more gullible). I can see people spreading false information with self moderated threads where they've liked their post with a lot of alt accounts. Anyhow, I'm not trying to say that this is very dangerous though. I'm just saying that we need to be aware of (potentially harmful) cases of abuse.
Remember, this forum is supposed to compete with other software that already contains this feature.
Sure. I wouldn't mind some 'thank you' or 'karma-like' system implemented (as I've seen in other locations).