I design everything myself, because I like to know exactly what I'm working with, but template sites are incredibly useful for coming up with ideas myself. When I need to come up with a design and my idea is looking kind of generic, or too similar to something I've done in the past, I'll check out template sites for ideas, or design sites like Zen Garden
or Smashing Magazine
. Smashing Magazine is probably my favorite out of all of those, though. They've got lots of general, technical, and "theory" articles on design.