man, i got my old '86 laying around here, and i've barely used it in the past few years. it's only done very simple calculations since i've been out of HS
i use to write programs, and all kinds of crazy shit on it. even built my own pc-to-calc cable to transfer stuff to it through the serial port. i had some awesome assembler games, and i even wrote a movie for it once. that was cool, but it used almost all of the calc's memory.
the '89 is sweet... i've thought about buying it just to have it, but the 86 does more than i really need, and it's definitely a lot nicer than the '83 i started with
edit: you know what the best part is? keeping this for 20 years to get laughed at by my children. my dad has shown me his scientific fancy-smancy ti calcs (even gave me one... it's around here somewhere), with red LED numeric displays. it's got about the same amount of buttons and stuff, but it's just got the mondo-cool red led display.
i wonder what tomorrow holds...