"Really clever sites have even found a way to bypass the signup form altogether. They slowly ask for data along the visitor’s path of discovery, and pretty soon

"Really clever sites have even found a way to bypass the signup form altogether. They slowly ask for data along the visitor’s path of discovery, and pretty soon she’s a member of the site, without having to fill out a form!" Be careful with this, it can backfire. Sometimes you come across a cool site that apparently doesn't require signup, then you spend some time creating something, and then at the last minute you get a message: "Ok, now to actually save your thing you just spent 10 minutes creating you JUST have to signup"... It's so frustrating I usually just walk away in disgust. Don't pretend no signup is needed to use a feature if it's not true.