TotalRecorder does the job, but it isn't free. The demo version will only record for 30 seconds. It's not very expensive, though (I paid $11.95 or $12.95 for it), and it's done the job well for me.

However, I believe those Bill D mentions are all free and they'll do the job too. I've used all of them, but I had already paid for TR and knew how to use it, so that's the one I've stuck with.