Looking at Tretter's boxes of stuff on the Human Rights Campaign (HRC), I think I can see a little more clearly what they have accomplished, and I'm thinking it won't be hard at all to produce a quality panel about them.
Basically, HRC is a lobbying group, also known as a "political action committee" (PAC). Much of their effectiveness comes from imitating previous powerful PACs like the Christian Coalition. Of course, not all GLBT advocates agree that this imitation was the right path for the GLBT rights movement.
Portrait of an Issue: 15 years of ENDA
HRC began helped introduce the Employee Non-Discrimination Act to Congress in 1994, and they have been fighting to get it through ever since. Will it finally pass in 2009?
HRC Lobbyists
Leaders who worked with HRC
Wall of Shame: Leaders HRC opposed