Do you have a SanDisk MP3 player? Do you use GMPC? Do you read this blog? I suspect that set is very small but if you are in this demographic here is a treat for you: a Ruby script to copy the cover art downloaded by GMPC onto your SanDisk device.
Here it is: sandisk-cover-sync.rb
Just run it with your device mounted under
/media and it will figure out the rest.
It should be easy to hack to work with other devices or Amarok, etc.