Each year, the California Medical Board disciplines hundreds of doctors, often suspending their licenses. This database lets you see all doctors disciplined in a particular area at once, or search for a doctor by name. It also shows California doctors with prior felony convictions, malpractice judgments, malpractice settlements, disciplinary records in other states and administrative citations. It's current through early June 2010; more doctors have likely been disciplined since then.
Note: Most California doctors are excluded from this database, because they have not committed any acts that are publicly disclosed by the state Medical Board.
Source: Medical Board of California. You can also search their official database.