I am a girl who LOVES a gadget. My new favorite: the key with a little flashlight embedded in the head. It's designed so the button is right where your thumb would be when you're opening your door anyway. I just bought one yesterday and it's just freakin' genius. I wish I'd thought of it. Totally worth $3.50.
My other favorite gadgets are my tiny Leatherman Squirt that I keep on my keychain, and the credit-card sized Swiss Army doodad that has a wee knife, a little flashlight, tweezers, a ruler, a magnifying glass and some other nifty stuff I can't remember. It fits in your wallet.
The *perfect* art-bidness gadget would involve a tiny level, a tape measure, and a flashlight, plus a few assorted tools (knife, screwdriver, tweezers). I'm still looking for that one.