I guess I do no apply to this thread because I live in Europe. But I'll participate none the less.

During week days:

-Hang out with my girlfriend;
-Hang out with my friends;
-Go to a bar (with one of the above or both);
-Computer;
-Writing/Drawing;
-Watch some Tv;

During weekends(I'll count friday as part of the weekend here, because It's different from weekdays):

-Sleep over at my girlfriends house;
-Go out to a dance club (some are 16+ and some are 18+. I'm 19);
-Go bowling with some friends and then eat at a very good secret place of us ;
-Wild parties at friends houses (not so much lately);
-Computer(beggining of the night or late in the night);
-Watch some tv(like when I'm going to sleep);

There's more but I think this is enough. It's true that US is overly screwed up when it comes going out at night if you're not 21+ (mostly). Our age limits here are 16+ and 18+. Drinking age is at 16.
If you're curious on where I live it's Portugal.