Gary Anderson Postal History - Postal History listings by State for 38 States plus Dakota Territory including many Doane Cancels. There are now separate lists of Doane Cancels for many of the States...
Jim Forte Postal History - Thousands of US Covers for Sale including many doanes.
Minnesota Stamp Co. - Has an extensive stock of US and UN Stamps, First Day Covers and collecting supplies.
Jim Mehrer's Postal History - Extensive Postal History Mail Bid Sales 6 times a year, Postcards, Literature and Supplies.
James E. Lee - Dealer in Philatelic Literature including all LaPosta Publications, Essays/Proofs, Fancy Cancels, U.S. 19th Century Stamps and Covers.
Golden Valley Stamp and Coin - Internet Auctions, Mail Bid/Floor Auctions, Stamp and Coin Supplies.
Dennis R. Abel Stamps for Collectors - Stamps and Covers for Collectors and the smallest auction on the Internet.
Filahome Philatelic Magazine - Philatelic Articles, Stamp Collecting Encyclopedia, New Issues and Philatelic Links..
All Stamps UK - All Worldwide Postage Stamps, free download lists and accessories.
Classic Philately-Till Neuman - Rare Stamps and Postal History Worldwide