And my favorite stick-um remover is Rubber Cement Thinner, which is gentler on the objects you're cleaning that most other solvents. Acetone in particular can eat some surface finishes you don't want eaten.
So far, I've only found it in art supply stores and Office Depot. Rubber Cement itself is everywhere, but the thinner is hard to find.
Cap it carefully and tightly, though, if you try it. It is so volatile it could evaporate overnight without a tight seal.
Deirdre