The projectt RetroAchievements (http://retroachievements.org/) tries to implement achievements for various games. It’s a really cool idea and can be a reason for some people to pick up old games again.
Would it be possible to implement this kind of system to libretro/retro arch by using the retroachievement database? We don’t NEED it but I think it’s an interesting idea. I’m quite positive the guys from RetroAchievment would love to help implementing it.