Trademarkia is in the business of assisting people with setting up trademarks. However, the also offer a solid (but basic vs USPTO) interface to the USPTO Trademark Database beginning in 1870.
What’s also interesting, potentially useful, and (dare we say) fun is the ability to browse trademarks by category. You’ll find the primary categories listed and linked on the left-side of the page and directly below the trademark search interface. There is even a tag cloud to see popular companies with trademarks. You can also search “inside” a category.
Some of the categories include:
+ Transport and Traffic Signs
+ Toys and Sporting Goods
+ Companies (McDonalds for Example)
+ Popular Companies by Number of Trademarks (as a tag cloud)
+ Telecommunications
Source: Newsycombinator
