My boss sent me a link to an article with this headline:
Survey Finds Consumers Buying Less Books Due to Current Economy
This is the result of all those damned signs in the supermarket checkout lanes. "10 Items or Less," they wrote, so that they could fit all the letters on the sign.
Less refers to single items of fluctuating size.
Fewer refers to countable items.
If we each have a glass of wine, and I drink half of mine, then I have less liquid in my glass.
If we each have three fortune cookies, and I eat one of mine, then I have fewer fortune cookies on my plate.
Less liquid. Fewer fortune cookies. That's my mnemonic device, and you're all welcome to borrow it.