Auction Sites
Auction Portals
Vendio	Vendio offers a number of services for that will help you to better utilize auction sites for both buying and selling with online auction sites.
BIG Auction Sites
eBay!	The granddaddy of auction sites.
Yahoo! Auctions	Not as big as eBay but pretty good.
Amazon Auctions	Looking better all the time.
No Fee Auction Sites
AuctionAddict	No listing or commission fees here.
Specialized Auction Sites
Beckett	Sports collectibles.
Shipping Rate Information
U.S. Postal Service Main Page	USPS Postage Calculator
United Parcel Service Main Page	UPS Quick Cost Calculator UPS Tracking
Federal Express Main Page	FedEx Rate Finder FedEx Tracking
Sources for Products to Sell
Surplus.net	Listings of surplus, closeout, salvage, and import/export items that you can resell.
Internet Marketing Association of Surplus Dealers (IMASD) Inventory Search	Same as above.
max-info.com's Below Wholesale Product Sources Page	Sells an e-book (book on CD) that claims to "contain over 5,000 Wholesalers, Drop Shippers, Close Out Sources, Import Trade Sources, On-Line Sources, Government Sources and More." I haven't tried it but just might. If anyone gets before I do though, let me know if you think it's worth the money.
Shipping Supplies
Fast-pack.com	Wholesale shipping supplies site run by Jason Archambault. Looks like a good option for online auctioneers wishing to save substantially on shipping costs!
Other Resources
Workz.com's Guide to selling with Online Auctions
max-info.com's "How to Master The Auction Sites"	Again I haven't ordered this but it looks like it might be good.
FeeFinder**	This shareware program calculates fees for regular auctions, dutch auction, reserve auctions and no-reserve auctions. It even lets you compare the costs of PayPal and Billpoint. It only costs $2.99 U.S. to register it.
Advice for Auction Sellers	Richard Seltzer's straightforward advice for free - not even any advertising at this great site.