I run AVENGEX, a tutorials, forums and resources community aimed at young webmasters.
I get a load of hits from guests every day from tutorial indexing sites, but most notably Google with about twice as many from any other tutorial index (mainly Pixel2Life.com)
I've been looking at getting some of these guests to register, and so far I've got adverts for guests only, meaning that when they register and log in none are displayed. I've also restricted access to the forums and some of the resources to members only. I'm also now looking at limiting guests to only 10 tutorials and then they will have to register.
I don't know where to go next, so have any of you lot got any criticism on what I'm doing already, or any other ideas? Perhaps a few case studies or examples could help.