I've got a few - my absolute favourite tool is a 1x30" belt sander. Now I've replaced the crappy belt that it came with for a decent one it's like a powered file and gets used for all sorts of things - chamfering shortened screws, sharpening tools and shaping all sorts of materials, including stainless steel.
Second favourite is a 4oz ball pein hammer I was given. It's nothing special, but it's just the right size for all sorts of little jobs, is well balanced and is light enough that you can't hit things too hard.
Third is a Bahco 1/4" hex ratchet set with a selection of hex bits and small sockets - perfect for fiddly little jobs like fitting mudguards.