One of my little goals for 2012 was getting better at using up what we had and throwing less food away, we certainly aren’t horrible at using stuff up, but there is always the stuff we just forgot about.
This little trick has been helpful, I’ll write the date, what it is, and how much of it there is on the container in dry erase marker, I just wipe it off with a napkin or my thumb before microwaving or dishwashing.  This is more helpful when freezing stuff, since when you pull what’s frozen you are way less likely to remember.
I especially like writing how much there is so I don’t have reweigh it to log it into MyFitnessPal.