These websites are for you choice. The first 4 are very useful, you can sign up to recieve weekly emails about the latest jobs. These are also the places where jobs are posted first before anywhere else.
http://www.hillzoo.com/ This will help you find jobs both on the Hill and around the Hill in DC.
http://www.fpa.org/ This will be useful for those seeking more then just a typical job.
http://www.unausa.org/ Joining this gives a person the chance to be a part of the community in DC that works with the UN and attend functions.
Accuracy in Media - http://www.aim.org/
Americans for Prosperity - http://www.americansforprosperity.org/
Americans for Tax Reform - http://www.atf.org/
America's Future Foundation - http://www.americasfuture.org/
American Conservative Union - http://www.conservative.org/
American Legislative Exchange Council - http://www.alec.org/
Capital Research Center - http://www.capitolresearch.org/
CATO Institute - http://www.cato.org/
Clare Boothe Luce Policy Institute - http://www.cblpi.org/
Competitive Enterprise Institute - http://www.cei.org/
Family Research Council, The Witherspoon Fellowship - http://www.witherspoonfellowship.org/
Hudson Institute - http://www.hudson.org/
Institute for Humane Studies - http://www.theihs.org/
Intercollegiate Studies Institute - http://www.isi.org/
Koch Foundation - http://www.cgkfoundation.org/
Media Research Center - http://www.mediaresearch.org/
National Journalism Center - http://www.njc.yaf.org/
Students for Saving Social Security - http://www.secureourfuture.org/
The American Enterprise Institute - http://www.aei.org/
The Federalist Society - http://www.fed-soc.org/
The Fund for American Studies - http://www.tfas.org/
The Leadership Institute - http://www.leadershipinstitute.org/
Young American's Foundation - http://www.yaf.org/