Two of the things I can't live without in my kitchen originally came from the office supply store: a sharpie and binder clips.
I keep the sharpie in my silverware drawer (not in a random kitchen junk drawer!) so I can easily pull it out and write the date on jars that I open. Spaghetti sauce, that interesting but slightly odd salsa we tried, half-used cream cheese now stranded without a bagel in the house--that sort of thing which can sometimes sit there for a while. Having the open date on there just makes it easier for me to see at a glance if a jar might still be viable or needs to be cleared out.
I use binder clips instead of those silly, giant clips to keep bags closed. I used to use clothespins, but I hate when they flip apart and I have to maneuver them back together. Nope, binder clips. They don't take up much space either inside the cereal box or in their container on my windowsill--and they're super strong, never fall apart and they're inexpensive.