Squeeze bottles, so handy, such a complete pain to clean if they had oil in them... I haven't found the bottle brush that makes this easy, yet.
One thing I've used over the years way more than I thought I would,
stainless steel steam table inserts.
-I have two large (2-3 gallon?) ones I use to cool down stocks, stainless steel is pretty conductive to temp transfer (the opposite of insulated) so plopping them into a cooler full of ice and putting small ice paddles in them will cool the stock down very fast.
-I have a couple small ones (1.5-2 quart?) that see much more action. I find they are the perfect thing to whip cream in with a hand mixer. They are a perfect match for my small immersion blender to blend my red sauce, soups, or whatever. I have a regular blender, but the insert/immersion combo cleans up so much easier, and when I'm done, it is already in a short term storage container.
Sizzler platters - I use these all the time when I start meat on the range, I'l move it to a sizzler platter before putting it in the oven to continue cooking while I use the first pan to deglaze and start a sauce. These are also great things to use in a toaster oven, they are just the right size.
One thing I notice when I cook in other people's kitchens is that many are missing what I consider a fundamental tool of cooking, some nice
heavy-duty stainless steel tongs. I'm not saying most people don't have tongs, only that the ones they have are flimsy and I hate them!