I use one I got given for a print size calculator. It's a bit dodgy as it's battery is hopeless and I have to remember to charge it regularly or it looses memory and I have to recreate the spreadsheet I use manualy because the software (ActiveSync) to connect it to the PC won't work after I upgraded it to the latest version, and reinstalling the old version no longer works either! Hey the price was right

Better than having a full sized laptop on the bench though.

As for using it as a safelight... I'd image a red globe in lampshade would be easier and more efficient, unless you were wanting to use it like a safelight torch.