I think of a new username every other day, but for the most part, I like to keep two usernames. One for personal things, all of which use the same username, and one for things that I wouldn't want an employer, for instance, to see. Mostly recreational things where I don't have to focus on something, like internet forums. But those I usually have about three usernames of the hundreds I probably have that I actually use. God I need a life.