CoCoRaHS makes its data available to meterologists, climatologists, and whoever else so they can study the weather, make better predictions, learn about microclimates and who knows what all. I just know it's fun when I report heavy rain or hail and then see the local weatherman announce my report on the news.
It's easy to be a CoCoRaHS volunteer. You do have to buy a 'fancy' rain gauge. My rain gauge will hold up to 11 inches of rain and will measure it to the hundreth of an inch. I know I'll need to be reporting snowfall this winter, which has never really been an issue for me before. I guess I'll have to view the on-line tutorial.
I also record my rainfall for my own use. Theoretically, if I can live in one place long enough, I can follow rainfall patterns to help improve my gardening. Theoretically.
Meanwhile my grass is overgrown, the weeds are getting high and the grass I had planned to remove around my new plantings is still in place. The good news is that I haven't needed to water any of my new plants!