Jerry’s Search Engine is specialised in dofollow / no-nofollow / ifollow blogs. And you can add your own blogs too (as long as they are part of the DoFollow movement, of course).
Curiously, I’ve been the one who discovered this site for StumbleUpon (my first SU discovery ever!). I’m amazed that the webmaster has failed to stumble his own search engine. It’s a very good idea, and will certainly be of interest to many stumblers.