The Oklahoma Medical Board has a searchable database providing licensing information on a host of medical professionals, ranging from Anesthesiologist Assistants to Medical Doctors to Therapeutic Recreation Specialists. You can find out the status of someone's license as well as any disciplinary action status.
Other states have similar accrediting bodies. Doing a keyword search for the organization and state may take you to the correct website. You can also visit a state's government website and find their list of state agencies.
The State of Oklahoma's website (www.ok.gov) has many great resources available to users. You can find information on Getting a Birth or Death Certificate, Lookup Offenders, and how to start a new business, for example. There are also links for searching legal and court documents, searching current and past bills, finding your legislator, checking business name and availability, business licensing, registered businesses public searching, find links to different state agencies, and much more.
A complete list of agencies is available at http://www.ok.gov/agency.php