1. TI-80: The first middle-school graphing calculator.
2. TI-81: My (and TI's) first graphing calculator (01991).

1. TI-82: Graphing calculator enhanced for statistics use.
2. TI-83: Updated TI-82.  This one is playing a game called Turbo Breakout (not very well, though).

     

1. TI-83 Plus: Newest version of the TI-83.  Upgradeable with Flash technology.  Mine has a nifty red (of course) cover and is showing here the results of a numerical integration program. 
2. TI-85: My second graphing calculator (01993) and still my primary working and teaching machine. A close reading of the screen will reveal this this caluclator breaks the 69! barrier by accepting numbers up to 10¹⁰⁰⁰.

1. TI-86: Updated version of the TI-85.
2. TI-89: The functionality of the TI-92 in the TI-8x platform.  This particular one is also overhead-projection compatible for easy classroom use.
3. TI-73: TI's middle grades graphing calculator.  This has some nice statistical capacities as well as full fraction operations.

1. TI-83+ Silver Edition: Introduced in 02001, this calculator is an enhanced TI-83+ with more memory and a faster processor.
2. TI-83+ Silver Edition Overhead projector model: This calculator is equipped for overhead projection and combines the power of the Silver Edition with the keyboard of the original TI-83+.

TI-92: The calculator with a computer algebra system, 3-D graphing, and a lot more built in.  I use this one with an overhead projection panel in the classroom.

Voyage 200: The latest (02002) product from TI, this Personal Learning Tool adds a graphical interface, clock, and several other new capacities to the TI-92+, while refining and streamlining the shape somewhat.

1. Casio fx-7000G: The first graphing calculator.  This one is showing my favorite function,
f(x) = e^{tan(ln x)}, on the interval (0,100).
2. Casio fx-7000GA: Second generation Casio, showing f(x) = e^{tan(ln x)} on the interval (0,10).
3. Casio OH-7700G: A graphing calculator designed for overhead projection.  On permanent loan from the Albion College Department of Mathematics.

fx-7700G: The line is extended further, including a more natural set of cursor keys.

For pictures of my HP graphing calculators, the HP-28S, HP-38G, and HP-48G, visit my HP Zone.