AuctionLink 
Creates short web addresses for eBay sellers that automatically link to users' current auctions. Free and paid options.
http://www.auctionlink.to/HammerTap
Offers a variety of software tools and web services to assist online auction users.
http://www.hammertap.com/
Auction Contact
Service allows sellers to send weekly updates to customers with direct links to auctions.
http://www.auctioncontact.net/
Vendio
Image hosting, store manager, customer manager and other seller services.
http://www.vendio.com/
The Seller Sourcebook
Auction templates, listing generator, image hosting, product sourcing guide and informational articles.
http://www.sellersourcebook.com/
Bay to Go
Provides SMS alerts to eBay seller's cell phone when a new bid is placed.
http://www.baytogo.com/
Auction Hawk
Services for general auctions on eBay. Images hosting, ad creation, scheduling and post-sales.
http://www.auctionhawk.com/
Auction Supplies
Shipping calculators, auction templates, practice boards, color charts and other tools for sellers.
http://www.auctionsupplies.com/
AuctionSage
Management and posting services for eBay sellers. Works with Bidville also. [Windows 95/98/ME/NT/XP/2000]
http://www.auctionsagesoftware.com/
AuctionProfits
An auction optimization service that uses mathematical techniques to find the best auction parameters in order to save time and earn more money for sellers. [Beta testing]
http://www.maxbidprice.com/
Ebaytools - Sourceforge
Free (Open Source) tools for watching, bidding, selling and searching on eBay auctions. All data and pictures stored in local SQL database for offline searching and viewing.
http://ebaytools.sourceforge.net
Auctiva
Provides a set of different services, including posting, showcase/image hosting, counters and feedback handling.
http://www.auctiva.com/
