Collecting
Bibliomania - http://bibliomania.net/
Features information for book collectors, buyers and sellers.
Collectorpro Software - http://www.collectorpro.com/
Provides software and services to the art and antique communities.
Stampcircuit.com - http://stampcircuit.com/
The virtual meeting place for stamp collectors, dealers, auctioneers and anybody who shares our great hobby.