I used to make fun of people who used salad spinners. The spinner seemed like such a '70s waste-of-space/invented-need gadget, and besides, how hard is it to drain lettuce? Then---surprise---we moved into a kitchen with a salad spinner, and I've been totally won over. It's amazing how much water a salad spinner can remove from rinsed lettuce, damp sliced veggies, etc. No more wet sandwiches, watery stir fries, or soggy salads.
Same thing with a kitchen scale. I was convinced people who went on and on about how great they were were just being pretentious. Plus, they're not cheap. But having actually used one regularly, I'm completely convinced it makes for better, more precise baking. It's great to be able to make metric recipes without all kinds of crazy googling.
What gadgets have you fallen in love with, despite your initial skepticism?