What is the most useful gift you've ever received?

radio/cd player for the kitchen.

We have no tv/view of tv from our kitchen, so my companion in the morning or making dinner is NPR or listening to music. I love that thing. I could put the stereo in the living room on, but I'd have to turn it up a bit to hear it in the kitchen, and since DH sleeps later, just having the one in the kitchen is perfect. I use it every single day.

My Shark steam mop.I have used it over & over & over.

A stainless steel spaghetti pot / steamer. We got it for our wedding over 25 years ago and I still love it. It is a tall pot (I've used it for canning), with a perforated insert, then there is another steamer basket that fits on top of that, plus the lid with little steam vents. I've used it to make big batches of pasta, for boiling potatoes to make mashed potatoes, to make corned beef, to steam tamales, cook seafood and blanch large quantities of vegetables to prepare them for canning. It is amazingly handy.

Mine was also a radio--a transistor radio.  Dh gave it to me for Christmas one year when we were dating.  I was so upset over that gift--you can't imagine.  We still use it today--it's over 27 years old--still works great.  We have it in the bathroom and I listen to it while I'm getting ready in the morning.  And we have used it many many times when the power has gone out.

Set of kitchen pans.

I have lots of these kinds of items. My DS's pack'n'play (never thought we'd need it but it is the only place he's ever been able to sleep comfortably), my dishes and my TV are all things that come to mind. The TV is old and used but we are so grateful for it!

This panini press that DH got me one year for Christmas.  I use that thing all the time.  It makes awesome grilled cheese sandwiches.