Shortcut or Life Hack?

I know you've heard of "tips" "shortcuts" and "tricks" but have you heard of "Life Hacks"?   That was a new term for me until just recently.  The definition of a Life Hack, according to Wikipedia is: any productivity trick, shortcut, skill, or novelty method to increase productivity and efficiency, in all walks of life; in other words, anything that solves an everyday problem of a person in a clever or non-obvious way.
Hmmmm, I've been doing life hacks for quite some time now and didn't even know it! I called it "recycling". For instance. using walnuts to fill in scratches on my wooden furniture ....or making my own icepack by putting a wet sponge in a plastic baggie and freezing it!  What's your favorite "life hack"?  Here are a few more I found from Twisted Sifter - give 'em a try and simplify your life! 

50 Life Hacks to Simplify your World «TwistedSifter