What websites have the best and most user-friendly login systems?

Question

StackOverflow does openid well and Quora does the Facebook connect and Twitter well....but one problem I had with Quora is that I can either login with my Facebook or Twitter account, but not both, so there is no way to import friends from both under the same account. Which is what lead me to ask here, in case there are other sites with good login models.

Answer 1

I like the way it works here in StackOverflow.

Answer 2

Pikchur has a pretty good system that accepts Facebook, Flickr, Twitter, and a number of other providers (mostly OAuth) and allows multiple accounts to be associated with your Pikchur account