For some time you could steal AOL usernames by registering i.e. 'obar' or 'oobar', and using client side hacks could switch the registration to the already regi

For some time you could steal AOL usernames by registering i.e. 'obar' or 'oobar', and using client side hacks could switch the registration to the already registered username 'foobar' which would then belong to you. This only worked if 'obar' or 'oobar' was unregistered, but it was a pretty nifty way to steal single word usernames, and speaks to some strange validation/truncation somewhere in the code.