I have to say that our handiest thing would be the dishwasher. None of us like to wash dishes and it's so nice to take the dirty ones and put them in the dishwasher until it's full. I love my dishwasher and I can't imagine being without it.
My pot holders! I am forever burning myself on hot pan handles or just trying to test something in the oven. So, I try to keep a lot of them handy and close by, saves a few minor burns.