I was cleaning up my nail stuff the other day and was pleasantly surprised to see that my (small) collection of Chanel polishes has held up well, even though many are five years old or more.
Some old favs:
Cobra (already mentioned)
Luna (Limited edition shade from long, long ago. Pretty pinky/slivery/blue; very sheer)
Cosmic Blue (late 90s)
Vertigo (Shimmery brown/red)