What's your favorite "reusable"?

The thrift store gives used cloth shopping bags away. I’ve been collecting them and taking them to the antique mall. I know they’ll use them, and that the cheapskate frugal ‘junkers’ will keep them in use until they wear out.

I have a hard plastic water bottle that I use, but, really, I feel like I could be doing more. All my plastic grocery bags get reused – not Earthshattering, either.

What’s your favorite ‘resuable’ that you get a lot of good out of, and that’s saving similar, otherwise disposable, items from the landfill?