What calculators do you own and use?
I have (and use)
Texas Instruments:
TI-84+, TI-89 Titanium, TI-30X IIB (a normal scientific, I have the white/silvery one, but, would love to get a purple/green/blue one, too) and a TI-80 which I got for $5 at a hock shop because it was cute and twee and baby sized.
Casio:
FX-100d quite a rare one. I have 2. It has hex, milli micro nano pico kilo mega symbols on some buttons (very bloody useful for electronics engineering)
Slide Rules:
Three, various kinds. Favourite is a Hemmi (Earnest) my then best friend got me from an op shop she worked at (with it's manual).
Computer:
A really old version of Derive (dos), copied from the computers at my high school back in 1991.
I'm starting to get into
YACAS, which I am finding useful.
I've used dodgies of Matlab and Mathematica, but, I'm not good enough at Math to really get maximum value from them.