Little bottles of nail polish can dry out or go bad, but think twice before you toss the jars into the trash. Almost all nail polishes (with the exception of a few eco-friendly brands) have volatile chemicals in them, like toluene and dibutyl phthalate. These chemicals aren't just flammable -- they are considered household hazardous waste. Because of this, they should be disposed of with other household hazardous waste when you have special collection days in your community. In some cities, it's outright illegal to throw old nail polish in the trash.

New York City's metro card system has eliminated tokens altogether, and those plastic cards can sometimes have small balances left on them going unused. One organization, the Next Stop Project, collects these low-balance cards and combines them to form full-fare cards that are donated to New Yorkers in need. Whether you're a full-time NYC resident or are planning to visit for work or vacation, don't toss cards that have value left on them. Learn more at nextstopproject.org.

Here's one reason to keep a can of tuna in your car: If you've ever seen a lost (and scared) dog or cat who runs the risk of being hit by a car, the best thing you can do to help is to try to lure the animal into your car. If you feel the animal is not a risk to you, the strong smell of fish can entice it to trust you and jump into your car. Be sure to have a can of tuna that doesn't need a can opener. When you do have the animal in your car, bring it to an animal shelter to be scanned for a microchip.