We have some tying stuff at http://www.flyfishersrepublic.com. Of course the pages right here at Fly Anglers Online are great, and several sites already mentioned are excellent: Hans Weilenmann's http://www.danica.com/flytier/ has really nice illustrations and recipes, globalflyfisher.com has some good stuff, and Paul Arden's http://www.sexyloops.com has some interesting articles.