What to do with extra lemon juice

I always have a lemon or lime in the fridge for fresh juice for many recipes I make.  But it occurred to me last week that I often end up tossing what ever I don't use.  I'll put the unused lemon in the fridge, but it doesn't last very long.  I hate wasting anything.  As I was making dinner,  it dawned on me that there has to be a way to freeze a lemon.

Freezing lemon juice

• Squeeze lemon juice into a pourable measuring cup. 
• Pour juice into a ice cube tray (the one I used were 1 Tbsp each). 
• Then put the ice cubes into a ziplock bag and use for individual use.  

So easy and great way to use up a lemon.