If you read New World Notes, one of the things you'll see Hamlet Au suggest as a way to improve Second Life (aside from point-and-click avatar movement :)) is some kind of achievement or ranking system (do read the followup, too; the link to Kanomi Pikajuna's parody of the idea in the article is now broken, but you can see it here).
The curious thing is that game makers are questioning the worth of achievement systems. In that regard, I highly recommend Chris Hecker's "Achievements Considered Harmful?" (One interesting datum Mr. Hecker mentions: "extrinsic motivations", e.g. achievement/ranking systems, tend to kill off intrinsic motivations more in women than in men--and Second Life, it is said, has a larger proportion of its user base that are (actually) women than other virtual worlds, so would an achievement system actually hurt Second Life, I wonder?)
I can't help thinking of a possibly analogous situation someone pointed out to me long ago. Back in the days when newsgroups flourished, there was one such newsgroup for Renaissance fairs, alt.fairs.renaissance. The folks who posted there typically signed their posts with their (persona's) name followed by an extensive list of self-assigned titles: "Joseph of Blowshire, Keeper of the Duke's Spittoons, Chief Cat-Herder of the Bloviate Empire, Lord High Pooh-Bah of Hand-kissing Certification..." I'm sure that it was in jest, but how different from the awards and orders in the Society for Creative Anachronism! In the SCA, one scrupulously avoids the presumption of assuming a title; such things are earned by right of arms, excellence in the arts and sciences, or service to the realm. They actually mean something. Game achievement systems, IMHO, don't.