In Oregon, I work for Portland Photographers Forum. We're a non profit organization that has several workshops this year. From film development, portrait, Van Dyke printing, platinum printing, street photography, and art of seeing. With these noted photographers, John Wimberley, Martha Casanave, Dick Arentz, Steve Anchell and Bruce Barnbaum.
All these workshops are at great value.
Visit www.portlandphotoforum.org for details or pm me.
They are a commercial directory...so how extensive it is rests on the workshop programs themselevs to get their entries in there and keep it updated.
Most other directories will be short on information or inaccurate with age. I think an updated workshop report list like the OLD one on photo.net would be useful...it should be easy to find, not buried.