From what I understand, MySpace got its initial group of users from (1) having a contest for parent company Euniverse.com employees to invite as many people as they could, and (2) spamming Friendster users, telling them about a faster alternative, when Friendster had performance issues.

MySpace also had a pretty good viral loop that went like this: 1) See small thumbnail image of Tila Tequila's boobs 2) Click image to see larger version, then forced to create account 3) Create account, use contact importer, email everyone you know

I think they didn't start throwing events until they were big.