Although I most certainly do not agree with Al Franken on all matters of politics, I do think he often proves good points, and his book "Lies and the Lying Liars Who Tell Them" was an amusing, sometimes laugh-out-loud funny, exposure of the country's...well...liars.
His radio talk show has been moved to Air America broadcasting and is available for download via Podcasts on the Internet. I started downloading a few and have mixed feelings.
One of the shows I heard, which interviews Tim Meadows pretending to be a black Republican Congress member, was kind of weak. Franken's voice becomes grating after a while as well - that low, whiny tone.
Sometimes the show has genuinely funny parts, but most of the time I was left feeling a tad unimpressed. I'd recommend his books over this.