The USPTO maintains a list of attorneys and agents with licenses to practice before the US Patent and Trademark Office. Currently, there are 10741 active agents and 31669 active attorneys. All searches reflect current information. Information concerning a practitioner's status as an attorney is based on records provided to the Office of Enrollment and Discipline and might not reflect the practitioner's status in a State Bar. Individuals interested in a practitioner's status in a State Bar should contact that State Bar for specific information.
I strongly recommend searching LinkedIN and reading the profiles of and endorsement of many patent attorneys/agents. I have received another inquiries from my site and i and others will often guide an inventor to a specialist.
Other sources include AIPLA-the American Intellectual Property Law Association, the American Bar Association, Section of Intellectual Property Law, Martin-Hubbell Lawyer Locator, and Alllaw.com which contains a number of links on finding a patent lawyer for a variety of patent needs, as well as a listing of IP attorneys by state.