Global Brand Database
53 million brands and trademarks, including 11+ million U.S. trademarks and brands
Global Brand Database (WIPO) Help
WIPO's Global Brand Database is about 3 times larger than USPTO's TESS, and appears to include all US trademarks. But TESS seems to have the more complex search engine, and better help links
Historical Patents and Trademarks
This collection of Microsoft Excel spreadsheets, donated to the Patent & Trademark Resource Center Association by Dr. Jim Shaw of Hutchinson KS in 2006, includes indexes of all US patents from 1790-1874, including nearly 10,000 "X-Patents" lost in the 1836 fire. PTRCA librarians added titles and addresses to the X-patent list in 2007
US Trademark Assignments Database
Trademark owners are not required to notify USPTO except when registering or renewing their marks, but most buyers and sellers of trademarks do choose to notify USPTO.
Other places to search trademarks
Google.com - to see if anyone on web is using your intended mark or name (or one that could be confused with it)
Newspaper and business databases (password remote login by UMD affiliates; guest logins on campus only)
