Not comparable but airpair have a similar trick, asking to signup if you want to see their whole samples http://i.imgur.com/pVuVjrY.png and not obfuscated code samples
I run a site (http://petihacks.com) with many of these little tricks if it's the interest of anyone
That would put me off using the site, let alone registering. Especially if it's meant to be social (i.e. I'm supposed to share links to content) -- I don't want to burden other people with the same hassle.
I run a site (http://petihacks.com) with many of these little tricks if it's the interest of anyone