If you're feeling like your MacBook or MacBook Pro is cool, but could be cooler, maybe it's time for a trip to Etsy to check out the selection of custom vinyl decals. For as little as US$10, you can make your MacBook a one-of-a-kind at the coffeehouse, and maybe even pick up a date for New Year's Eve (although the latter depends greatly on your personal abilities to do so).
There's a pretty wide selection of decals at Etsy, but one artist in particular has caught my fancy. Ivy Boersma, a.k.a. IvyBee, has some designs destined to be classics. I'm especially fond of the William Tell and Newton images, but it's obviously subjective. There's enough variety that you can find something that really fits you, and carry it as a classy and subtle expression of your personality.
Ivy also offers custom designs upon request, so if you don't see what you want in her online shop, contact her through Etsy (just sign up for a free account) and let her know what you're looking for.