Many people don't want to give out another e-mail or another password to yet another site. Given the Gawker and other leaked account debacles, many people use

Many people don't want to give out another e-mail or another password to yet another site. Given the Gawker and other leaked account debacles, many people use the same login/authentication across web services. By using my Facebook login, I put more trust in Facebook securing my credentials vs. a startup I barely know anything about. Plus, it saves me tons of time.