The Denver Public Library has an interesting calculator of library value for taxpayer dollars invested. It's a publicity tool, so not a great deal of information about how the numbers are arrived at, but interesting all the same. To an extent public libraries are just a highly-structured, taxpayer-supported form of resource pooling--a much more sophisticated version of when I pooled my money with my best friend in 1988 to buy a Sega Master System that we transferred between our houses every two weeks. :) I suppose a calculator like this reveals explicitly just how much value you're getting for your tax dollars vs. your usage, which has some potential pitfalls as well as benefits.