Biographical Directory of the United States Congress
Biographical directory of all members of Congress since 1774, committee directories, financial disclosure forms, etc.
Congress.gov
The Library of Congress sponsors and maintains this database for information on presidential nominations, executive communications, treaties, federal legislation, committee information, and other congressional activity.
Enigma.io
Enigma hopes to become a Google for public data, standardizing and connecting all kinds of data from government agencies, companies, and other organizations.
Federal Election Commission: Individual contributions
Browse Federal Election Commission (FEC) campaign finance data on individual contributions
Opensecrets.org
An alternative way of searching the FEC’s database by donor name to find individual contributions to political campaigns. You can also see the top donors to a candidate’s campaign, lawmakers’ net worth, and more. Brought to you by the Center for Responsive Politics.
The Political Graveyard
Appears to no longer be actively maintained, but this resource provides historical information on living and deceased politicians which can be used to ascertain whether or not a prospect was ever related to a politician, judge, or diplomat. Most of the people listed have ended their political careers. Searchable by name, office and state held, date born or died, state and county of birth or death, ethnicity, religious affiliation, awards, military status, etc.
United States Government Policy and Supporting Positions (Plum Book), 2016
The Plum Book identifies presidentially-appointed positions within the Federal Government, and is published every four years, just after the Presidential election. It can be used to find the salary and names of Federal employees, including Presidential appointees. You must know the department the person is in.
USAGov
Excellent starting place to find information about anything federal. Includes links to state and local governments. It is really a search engine devoted solely to government.