Flagging something puts it into a database that admins look out and then clear. It's not a good idea to put merits in there too, the spam would simply cover it.
We use to have a mark-up button, but it was taken down. Either optimization or abuse of the function.
flag = spam/abuse and when it's flagged enough, the mods will look at it.
I think pretty much every activity on the site will also have a 'like' button, and when enough people 'like' something, the author might get extra karma/points.
