The fastest way to add cover art to a podcast folder on an MP3 player running Rockbox:
- Browse to the raw feed using Firefox
- Press Ctrl+U
- Type /:im (this finds the Apple iTunes image tag, the best image to use for the podcast)
- Copy the URL of the iTunes cover art image
- In a bash terminal window, in the podcast directory, type wget `xclip -o -d` ; convert *.jpg -resize 100x100 cover.bmp ; rm *.jpg
You'll need to be using Linux, and have xclip and convert installed, of course.