Recently I came across this post which looks at an emerging issue with a user's ability to login using authentication via an entirely different service, such as Facebook.
This is a login option I don't tend to use - I prefer to keep everything separate - but I thought these stats were interesting, noting how often folks end up with multiple accounts and still can't remember their login:
"User Interface Engineering's analysis of a major online retailer found that 45% of all customers had multiple registrations in the system, 160,000 people requested passwords per day, and 75% of these people never completed the purchase they started once they requested their password. Ouch."
The folks at bagcheck illustrate an approach they're trying in order to help make this type of login easier for the end-user. I like that they show they're process and how it evolves.
What does strike me as odd is that you can see all these other user names when you search for your own... that seems worrisome.