United States Patent and Trademark –
The United States Patent and Trademark Office within the Department of Commerce site contains a searchable database.

United States Copyright Office within the Library of Congress –
US Copyright Office is an office of public record for copyright registration and deposit of copyright material.

European Trademark Office –
The European Trademark Office site contains information about patent protection in Europe.

Google Patent Search –
Google Patent Search covers the entire collection of patents made available by the USPTO: from patents issued in the 1790’s through those issued in the middle of 2006.

Delphion Intellectual Property Network –
Delphion Intellectual Property Network has searchable databases on patents and related information.