Terry Gross

He is also known as "Questlove" of the hip-hop group The Roots. The Grammy award-winning sextet has six albums to its credit. Their latest CD is Phrenology. Their first single from the album is "Break You Off." One reviewer writes, "To fully savor the sound, you've got to commit to spending time with The Roots, to wallow in both the music and the message.

Stand-up comic David Cross co-created the 1995 HBO cult hit Mr. Show (an amalgam of live sketch video pieces and occasional animation). He also wrote for the short-lived Ben Stiller Show. One reviewer writes of his act, "foul mouthed and razor sharp, doesn't shy away from vicious social criticism and outright political dissent."

He is a former U.S. ambassador to Croatia, and is now professor of national-security studies at the National War College in Washington, D.C. Since the late 1980s he has been tracking Iraqi war crimes. He has also worked closely with the Kurds — who control a small territory in northern Iraq. Galbraith will talk about what a post-Saddam Iraq might look like.