I haven’t played many browser based games. I only test some Flash games and forget them right away (there are tons of quality products though). I think Urban Dead has been a browser game that I kept playing for some time… until I forgot it too.
I think I’ve never paid a cent for these games, but I think I’ve clicked some ads some times.
At some point I played Mafia/Werewolf forum version in various places, but also stopped that.
What’s the best browser based game you’ve ever played? Have you paid for any of them (like purchased in-game items or whatnot)?