I found these online fly fishing magazines off two different forums I visit also. They are both online only, that is why the pictures within each of them are extremely vivid.
The first one, This is fly, is more of a younger generation hip magazine. Regardless of the cover, it is actually a pretty good magazine.
This is Fly | Fly Fishing Magazine
The second one is by far my favorite, it is brand new, and it has the best pictures ever in it. Short on articles but wow the pictures are amazing.
Catch Magazine - Fly Fishing Photography - Film - Video