If you are looking for a way to hide a key outside, a pill bottle makes a great weather-proof container. With a rock to disguise the top, you can tuck it into a rock garden or partially bury it to hide its location.
For camping or late nights at the beach? Leave 1/4 of Mountain dew in bottle (just dont drink it all), add a tiny bit of baking soda and 3 caps of peroxide. Put the lid on and shake - voila! Homemade glow stick (bottle) solution. - Click image to find more DIY Crafts Pinterest pins
How to fold and store plastic grocery bags. Literally the best thing I've seen all day. I try to avoid plastic bags when I can, but whenever I end up with them I save them to reuse later. Right now they're taking over my kitchen, but this is a much better way to keep them contained.