Vinegar

• Vinegar can also be used as a solvent for removing the adhesive residue tapes leave on glass and plastic. It works well for quickly removing an adhesive residue that has been left on for about 1-2 weeks. To remove the adhesive residue using vinegar, you should:

1. Apply the vinegar to a cloth or paper towel.
2. Dab the cloth or paper towel in a little bit of vinegar.
3. Scrub at the surface with the damp side of the cloth or paper towel.
4. Dry the surface.

from Wikipedia.

Guess what? It also works on the glue residue left on my linoleum! My entry room smells like vinegar now. *sigh* But the test spot came right off! Very cool.