Achievements and Gamerscore.
Everybody can see how many games you've played and how good you are at them, on Xbox Live, and PS3 Home is getting a system like that as well. I had a discussion about it with some of my friends the other day, main question was this: Are Gamerscores important (do you try to get every achievement etc) or are they just a tool for playing a digital game of ''who has the largest penis''?