Photo Focus first runs entirely on questions about photography presented from users, done by a person who is well known for sharing his tips and an excellent photographer, Scott Borne. I follow him on twitter, and have learned tons from him, he is @ScottBorne. I've learned a great deal from him already, and I highly encourage you to follow him if you are interested in photography.
The second, Tips from the Top Floor, is more geared to the higher end photographer, perhaps the prosumer level. Still, it has many tips, including things to increase creativity and improve your photography. You can follow the main producer, Chris Marquardt, at @chrismarqardt on twitter.