Stanford University researchers discovered that users of virtual worlds like Second Life with attractive avatars were more confident in real life.

Newsweek:

In one Stanford study, volunteers were assigned avatars who ranged from attractive to plain. It is one of life's inequities that the world sees attractive people as possessing a long list of desirable traits, including honesty, generosity and kindness. Perhaps as a result, people judged attractive are more self-confident than ugly ducklings, and so tend to be extroverted. Using a virtual-reality headset, the volunteers—actually, their avatars—walked across a room to interact with another avatar. Those with attractive avatars got within three feet of the stranger; those with homely ones kept almost six feet away. How much "personal space" one needs is inversely proportional to self-confidence, which having an attractive avatar increases. When the stranger asked the players to "tell me a little about yourself," good-looking avatars revealed more: feeling attractive increases self-esteem and therefore friendliness.

The Proteus effect spilled into the real world. After their virtual-reality session, players were shown photos from an online dating site and asked to pick those who "would be interested in you." Players who had been assigned attractive avatars picked more-attractive candidates than did players (of equal pulchritude in real life) who had been represented as homely avatars. Male players were also asked to enter personal information for an online dating site. In this situation men routinely inflate their height by an average of one inch. But those who had had an attractive avatar told the truth.