topozone.com IS a good one. I also came across topowest.com. Check that one out too. I don't know if you can do this on topozone, but you can have the option of having them print the topo map that you find on the site, and then you pay money and they send you a real map of what you found, so that's kinda cool. You can also view their maps at like 25, 50, 100 and 200 DPI for better/worse resolution.
-Brian