Bit late to the day on this, but . . . Lighter Fluid (benzene) - I use Swan, the liquid one, not the pressurised one. It cleans sticky stuff, cleans metal on cameras, and I've even had it remove wetting agent residue from the non-emulsion side of film (honest) with no detriment. As with all things, caution works best, but it can be done.
It's my miracle work around for lots of things. Doesn't melt plastic cd boxes either.
With removing stickers your best approach is to carefully try and remove the sticker, if it peels and leaves a residue, try and remove that by sticking and lifting with the sticky side of the removed sticker. This often works, failing that . . lighter fluid!