The dudes from DotNetRocks have created PWOPCatcher - a PodCast download and organization client. Eventually it will keep track of a "listened-to" attribute of downloaded podcasts, which is exactly what I've had to maintain a text file for :)

It's written as a .NET 2.0 (of course) WinForms app that deploys with click once technology. It's got killer alpha-blending and skinable interface. There is still a long way to go from this alpha, but something to check out.

Intellectual Hedonism - Pwopcatcher Alpha