Show us a gadget you can't live without.*
This is a grater made by Microplane–they only made wood tools until the wife of someone in the company grabbed one for her kitchen. Someone should buy one for you for your favorite winter holiday (they run $12-15).
*Truth is, if we're really going with "can't live without", AuntieMallika's answer wins in all categories (have you thanked your plumber for making modern civilization possible?)