The best thing they every made was Slow Cooker Crock Pot Liners. I use my crock pot weekly, and the worse thing about using a crock pot is the clean up.
With the Crock pot liners, you can cook your meal in the crock pot and as soon as your are done, you just lift out the bag and voila, you have a practically clean crock pot! Wipe it out with warm soapy water and let it dry. You are ready to go again!
Addendum: According to "Good Housekeeping" the Reynolds Slow Cooker Liners are PBA free and safe to use.