Before you go any further, allow me to clear some things up.. I have one TI-83, one TI-83+, two TI-86's, and one TI-89.
What is a TI graphing calculator?
If you are in high school, odds are that your school makes some use of them. THey can do very complex problems, and graph equations. They are also capable of playing games on, which is a nice plus for students.
What calculator is right for me?
If you don't have any calculator yet, don't get one just because everyone else has it. This especially applies to the TI-85. A lot of people have the TI-85 because it was one of the fist graphing calculators Texas Instruments ever made. If you're just starting high school or even junior high and have no experience with graphing calculators, you'll want to get the TI-83+. It is the easiest to learn in my opinion, and that is what I started out on. But, If you're really good with computers, programming, and whatnot, the TI-86 might be right for you. I'd suggest you find someone who has each one and try them out for a week or two before buying one. But whatever you do, do not get a TI-82 or TI-85. These have been replaced with the TI-83 and TI-86 respectively. There is a TI-83 and a TI-83+ out. The TI-83+ is simply an improved version of the TI-83 with some more capabilities. You might see someone with the TI-92 and think "Holy **** that is pretty cool!" Well, it is and it isn't. Since the realease of the 92, TI has come up with the 89 which has almost all of the power of the 92 plus more all in a smaller case. The 89 is allowed on far more standardized tests that the 92. That is because the 92 is considered a computer because of it's qwerty keyboard. I would not reccomend either of these for someone starting out. I originally got my 83 thinking "Wow, I can play games all class!" While this may be true, you can't always get away with it. If you're over in Europe, you might be in luck. I don't remember which countries, but in a few of them a teacher clearing the memory is considered vandalism and you could probably press charges. Here in the US, as far as I know, no one has pressed charges yet. So, teachers can ask you for it and/or clear the memory. Yes, there are ways around this, but I won't explain it now. If you want it just for the games, you might as well get a game boy. If you actually learn a little about it, you'll learn that you can use it greatly to your advantage (at least for math class). The main reason it's called a graphing calculator is because you can graph stuff like "y=2/3x+2.3" If you use it to your advantage, you will do way better than if you were just playing games. Trust me, many a times it has saved me.
What are some other good TI graphing calculator sites?
How can I learn TI-BASIC, the built-in programming language for the TI calculators?
Read the preface, and that will lead you to the tutorials. The preface contains much important information you should know. If and only if you have already read the tutorial, you may proceed to the proper page:
How can I learn assembly, the other programming language for the TI calculators?
I have future plans to make some tutorials for assembly, however, I have none at this time. If you are really interested, check out the links above to other TI calc sites.