This is the world's simplest podcast (RSS enclosure) downloader. You just paste in an RSS URL, and then whenever you click "refresh", it looks for new issues of your favorite podcasts. Then it lets you select which ones you want to download to SD (/sdcard/Podcasts).
Free, no ads. This app is the sort of open source where no one has bothered to upload the source yet, but you can email me and I'll send it to you.