A few links -- I am just scratching the surface here... More soon.

Custer Forge & Welding - my Blacksmithing teacher
Anvil Fire - a leading online forum for Blacksmithing
The American Bladesmith Society
Budget Casting Supply
Ernie's Massive Metal Links List
Rec.Crafts.Metalworking
Association of Backyard Metalcasters -- Links
Beautiful Iron
Hobby CNC