I posted this a couple of months ago, but I might as well post it again since it's Christmas.
Well, you can use it for what I use my Mac for:
Get Parallels and run Windows so you can do Windows like things. (I don't do that often, have a Windows laptop for that.)
Record iTunes/Streaming radio from internet radio stations with Audio HiJack pro. (I'll probably get an infraction from that statement...fair use guys.)
Use Audacity or Garageband to break the songs up and tag them to import into iTunes.
Make Silly little videos that you can post on YouTube for your friends to enjoy, and your enemies to mock you for with iMovie.
Work on your resumé with iWork to get a better job than the seagull micromanager you used to work for.
Pick up chicks at the Starbucks because they'll be all "oooh, and aaaah" that you're using a Mac. Or perhaps get a small dog. Maybe that might work better.
Use the iSight camera to video iChat with your other Mac owning friends.
Download and use Google Earth to locate places you might need to visit. Good for when you're gonna travel in your next job for figuring out where the hotel is. Helps if you have a GPS receiver.
Use the iSight camera (again) to take silly/goofy pictures of yourself for your Myspace page.
Use the iSight camera to take silly/goofy pictures of yourself for your Facebook page.
Use iWeb to gussy up your website for your friends or mocking enemies.
Refine your UNIX command line and shell programming skillz by running terminal and running scripts you wrote when you were a Linux user. (May not apply.)
Get an Epson printer that prints on printable CDs to make CDs and DVDs from those recordings you made earlier that you burned (have I gotten my infraction yet?) I was using my own photographs, but iTunes has a dandy printing function that makes great CD/jewel case labels with the album art.
Put on Pink Floyd's "Dark Side of The Moon", or even better "The Delicate Sound of Thunder" on iTunes and turn on the visualizer. Veg out. Try not to have a seizure. Might want to get some mind altering substances, like V8 low sodium vegetable juice.
Use Bitpim with the built-in bluetooth to create your own custom ringtones and download pics you take with your cell phone.
Musician? My brother-in-law is. He uses his Macbook to make his own music and publish it (no infraction here, he's not signed and it's his own stuff.) Do that. Perhaps learn the guitar. Been meaning to do that.
You have in your posession the best notebook computer known to man. I think you can figure out what you can really do with it. These are just a few mild suggestions.