I'm jumping on Tomato's bandwagon. Herewith, my most useless kitchen tool: turkey turners.
In 1998, when we moved from Shanghai backback to San Francisco (a stateside interlude that ended with our relocation to Bangkok a little over three years later) I went a bit kitchen acquisition crazy. I'd bought virtually nothing for the kitchen since we left the States in 1994 and reacted by going overboard. These turkey turners are the most useless of my useless tool acquisitions during that heady period.
They're useless not only because turkey is never on the menu here at Chez Eckhardt-Hagerman in Kuala Lumpur, but also because piercing a turkey's skin is exactly what you don't want to do when you turn it. You want to keep that skin intact, holding all the lovely juices in. And, as I learned the first (and last) time I used these things, they're damn unwieldy when you're trying to maneuver a sixteen-pound carcass. Two wads of paper towel accomplish the job much more efficiently.
I guess the only question is, since I haven't used these things since November 1998, why do they still occupy space in my kitchen drawer? More to the point, why have I moved them from San Fran to Bangkok, from Bangkok to Saigon, and from Saigon to KL?
Into the bin with them.
Update: Apparently us useless kitchen tool owners are asked to also name our most useful kitchen tools. That's easy: an excellent knife, a knife sharpener, a good cutting board, a mortar and pestle or other grinding mechanism, and a silicone spatula (doubles as spoony thing and spatula to cook with).