Google has released a search engine for patent searching which you can find at http://www.google.com/patents. There are currently over seven million US patents in the search engine. You can do a simple keyword search or explore the advanced search which allows you to search by title, by issue or filing date, by inventor or assignee, and more. The results include the title of the patent, patent number and date of filing, and a small excerpt.

Tips courtesy of http://www.researchbuzz.org