General Information Concerning Patents. This guide from the USPTO explains what a patent is and how to get one.
Conducting a Patent Search. A 50-minute presentation from the USPTO, explaining how to conduct a patent search and why it is important to be thorough. [Flash is required.]
Basic Facts About Trademarks. This guide from the USPTO explains what a trademark is and how to get one.
Trademark Information Network. The USPTO has created a series of newscast-style videos to help you understand trademarks. Check them out!
International Patent Protection. Links to information at the USPTO site about the Patent Cooperation Treaty, Common Application Format, and more.
Espacenet. Search patent documents worldwide from over 72 countries and regions. WIPO (World Intellectual Property Organization) Intellectual Property Digital Library. Search international trademark registrations (Madrid system), international patent applications (PCT), and other databases; access guides, standards, laws, regulations, fees, statistics, FAQs, links, and more.
There is currently no internation open web trademark searching site.