The Juice Receiver was formerly (and probably better known as) iPodder. It is a multiplatform Open Source Podcast aggregator client. It was the first podcast receiver I used (first on a Windows PC and later on a Mac until iTunes added podcasting features). I still use it on the Windows side for the few podcasts that do not go on my iPod.

Windows Vista users may run into a glitch when attempting to run it on that new OS release. However, there is an entry in the Juice Receiver Support Programs that explains how to use it under a Windows XP SP2 Compatibility Mode for use with Vista:

JuiceReceiver Support: Running Juice on Vista [FIX}