Clearance Sticker Gunk Removal

Why do Stores always use a cheapy clearance sticker to stick on glass? Well the WD-40 pen is a favorite tool of mine to remove sticker residue. It's so little and you can be so precise with it with no spray mess. I also heard orange peel and Goof Off work great too.
Tonight I tested the orange peel method, and guess what it works beautifully. Look at these before and afters.
1. Peel off what you can. Remove the rest of the paper with a little water on your finger.
2. Now you have the sticker gunk.
4. Rub your orange peel around. Switch around on the orange peel, when the peel starts getting sticky.
5. And viola gunk free. The juicier the orange peel the better.
What else works for sticker gunk removal?