Hmm...my roommate was so into Brain Age he bought a DS lite from gamestop.com. Well, the shipping got delayed by about 3 days, and he was so frustrated because he wanted it asap, he sold the one on order to our other roommate for $100 (with Brain Age!) and went out and bought the system + game retail!
That's right, he took a $50 loss to get it 3 days early, and this guy doesn't really have that kind of money to throw around, which just goes to show how much he wanted it.
Another friend of mine wants one, but is afraid it'll distract him from school too much, or else he'd already be in.
So, 3 for me, myself included.