There are quite a few sites out there that provide good information on fly fishing but we found Troutnut.com as a very comprehensive source for many anglers and all aspects of fly fishing. The website is a graphic monument to trout, fly fishing, scenic rivers, the fascinating flies we all try to imitate, and how to match the hatch for every common species in North America. It is run by “Troutnut” Jason Neuswanger with help from many others.
They’ve also got a lively fly fishing forum, so look it up and say hi!