I don't care about achievements but I like the idea of sharing things with your friends. For example, in Mario Kart you get 3 stars when you're really good, so why not sharing that information in your profile? Things like that would be cool to see.
Castlevania Judgment FC: 1161 - 3389 - 1512
3DS Friend Code: 3480-2746-6289
Wii Friend Code: 4268-9719-1932-3069