CG Cookie just launched a new workshop on topology.
Models are the center of everything created in 3D, so they're important to create properly. Topology is how a mesh's vertices, edges, and faces combine to form shapes, and good topology uses those components in the most practical way possible. In this course, you'll learn a slew of mesh editing and selection tools, as well as how to use them to create good topology. By the end, you should be able to model anything that you set your mind to.