United States Patent and Trademark Office www.uspto.gov/main/patents.htm
This is the ultimate source. If you can spend some time learning to correctly search within the Web site, you will get the best results. Remember, when you are searching for a company, refer to it as assignee. Separately, search the assignee or the town, if small or unique, (skip New York and Los Angeles), and search for the inventor by last name. Other reliable sources include:
www.freepatentsonline.com -- Indexes the full page, but does not give the full results.
www.patentgenius.com -- Excellent search capabilities but, unfortunately, the results are limited.
www.google.com/patents -- Does not index the full page.
Note: This tip is from Cynthia Hetherington's book Business Background Investigations
