This week, I stumbled across bugmenot, where people can share logins for all kinds of sites. E.g. this one for soundclick, an online music site. I like to listen to fellow amateur composers, but I categorically refuse to register for these sites. There are too many, and i don't see what value registering provides me...
Unlike some other sites of course, where registering does provide value. For instance, forums such as synthforum.nl where registration makes it easy to follow who says what. bugmenot allows me to decide when I find it valuable enough to register, and when not.