“NASA has an overlay for Google Earth that provides a quick visual representation of of how much rainfall has occurred in your favorite foray area at http://pmm.nasa.gov/node/189. Scroll down the page to the Hourly Rainfall Accumulation and download the KML file to view rainfall accumulation for the last 168 hrs (1 week). This is continuously updated, so if you are trying to track rainfall for more than a week you will need to look at it every 7 days and create your own cumulative record.”
I tried it and it works as advertised. I would note that you can see the translucent coloration that marks the areas of rainfall a little better if you click the “Sun” icon at the top of the screen and adjust the slider to make the underlying terrain darken like nighttime.
I still think the water page from Weather.gov is the most useful resource of this type, but this one definitely has potential.