I made YouCast that allows you to subscribe to channels and playlists on YouTube as video and audio podcasts you can track in any podcast app.
It's great for tracking your favorite channels without blowing up your mobile plan and battery.
It's basically a WPF app with a self-hosted WCF service that uses the YouTube API (v 3.0).
You are more than welcome to take a look, contribute, critique, etc. It's on github here, and I'm on twitter here.