Auctions 
Course teaching how to sell on eBay with 16 hours of online instruction taught by a 10 year eBay veteran. Education on how to have an eBay business instead of an eBay hobby. Based in GA, USA.
http://www.auction-genius-course.com/
2. Christie's
Premier auction house offering live auctions. Provides information about how to bid and sell, auction calendar, sale catalogs, sale highlights and results, and an invitation to consign items.
http://www.christies.com/
Auction resource for UK bargain hunters. Lists government auctions, police auctions, liquidation sales, and bankrupt stock sales.
http://www.government-auctions.co.uk/
Provides a full range of services for trust and estate professionals in addition to art.
http://www.lesliehindman.com/
5. Sotheby's
Premier auction house offering both live and online auctions. Sells items such as art, antiques, books, jewelry, and collectible memorabilia. Features online catalogue, auction calendar, and advanced searches.
http://www.sothebys.com/
6. Swap Thing 
A new and exciting way to get desired items or to get rid of undesired items without any cash.
http://www.swapthing.com/