The coffee grinder because it's so darned noisy - scares the heck out of the cats and I'm always afraid I'm going to chop my fingers off with those sharp blades. I had one go berserk on me and I couldn't turn it off; had to unplug it - it was possessed!
and my Geo. Forman Grill - that's a love/hate thing: Love the way food turns out cooked on it but it's a BEAR to clean!