Removing a label's sticky residue from a book cover
1. Remove as much of the paper label as possible;
2. Smear on a little peanut butter on a paper towel;
3. Leave it for a few seconds;
4. Remove the residue with a piece of clean paper towel;
5. Repeat 2-5 as necessary;
6. If it smells a little peanutty, put a tiny amount of washing up liquid on another piece of paper towel and wipe off.
I just did this on the cover of a paperback and there is now no trace - so I'm very impressed.
The chemist in me found this interesting -I'd guess that the peanut oil weakens the bond between the glue and the surface of the cover, and the ground up peanuts act as abrasive to remove the scraps of paper and polymer. Then the detergent picks up and removes the traces of oil. It would be quite interesting to analyse a little further.