Not that anybody asked me, but I'm going to give a word of advice to college and high school grads from someone who has been out of college and high school longer than he cares to mention and has made the mistake he doesn't want you to make. Here's my one bit of advice:
Don't loose track of your friends!
I know you think you'll stay in touch, but things happen, you get busy, and probably you'll slip. People will move and forget to let you know, or get married and change their names. So, in addition to getting their current email address, phone and mailing address, learn your friend's parents' names, address and phone number (parents are a bit more settled and less apt to move around). Learn your friends' full names. Is it Kim or Kimberly or Kimberlee? What are their middle names? (Believe me, it's a lot easier to find a John Danforth Smith than it is to find a John Smith). Then sign up with something like Classmates.com.
In 10 or 15 years you may be very glad you did this.