This doesn't really seem immune from spam. I got signed up for goodreads (book review site), and I get tons of spam. It's not quite the same as your idea, but

This doesn't really seem immune from spam. I got signed up for goodreads (book review site), and I get tons of spam. It's not quite the same as your idea, but it is a currated list. I don't know how you stop spammers from adding bogus links in the python interest list (to use an example). This is a hard problem.. EDIT: Clarified goodreads reference!