I've got several specialty items that I've used one or only rarely, purchased for specific tasks. Here's a couple that I at least thought would see more use:
I bought the Gearwrench set of panel removal pliers, haven't used them once.
I picked them up shortly after leaving a auto tech job where, at the time, I didn't have any good options for popping out those plastic rivets and was doing so on a daily basis, usually with just a flat blade. When I saw the set on sale I assumed I had to have them - but now it's been over a year and I haven't had occasion yet (I don't turn wrenches for money anymore). I'm sure they will come in handy eventually though.
Tri-jaw bearing puller:

I've made do without a tool like this numerous times, but eventually picked one up to help me remove bushings and seals from the load bar on a neighbor's John Deere 4020. At least a couple years have gone by and I only just remembered I have it when I went to reorganize my tool box a couple months back.
Inspection camera:
Doesn't this just seem like a useful tool? This was another of me finding a deal on something I assumed would be great of only I owned it. Instead I forget it exists all the time.