Texas Instruments TI-83 Plus Graphic Calculator

I needed a graphing calculator for freshman year of high school last year, and I spent a hundred dollars on this one, which is the second-newest in the line.
I still haven't figured it out completely, but there is a helpful five-million-page guidebook to use! There's every function you could imagine, and files where you can program in formulas and store answers (can you say "cheating"?)... it's like a hand-held computer. You CAN type on it,but you can't save what you write.
By hooking upto a computer, you can download games from A to Z, and the memory suffers only a little as you get hundreds of thick files- that is to say, it uses a little more battery power, even when you're not us=ing the programs.
Aside from the price and the slightly daunting task of figuring it out, this is a great investment and a useful mathematical tool.