The Toucans Ramphastids Yahoo Group
I've found this to easily be the most useful toucan resource on the net. It is a pretty active, and generally quite responsive group of toucan owners, including some very experienced breeders.
National Finch and Softbill Society
NFSS is an organization dedicated to the "conservation, breeding, exhibiting and enjoyment of finches and softbills."
A great forum for pet bird owners and breeders. They have somewhat active softbill and toucan sections, and some pretty knowledgable members.
The Perch.net was a great forum for toucan owners, but sadly it is down for the forseeable future.