To go along with my interactive Google Map, I've created a series of kml files which I have really enjoyed playing with. Unlike the Google Map, the kmz file attached includes different layers for all NSS internal organizations including Grottos, Surveys, Regions, and Sections. I also like the behavior of the kml files better, so if you use Google Earth they are worth checking out. All information is current with what is posted on http://www.nssio.org/. All locations are based on the mailing address on record. In some cases this means the address is a "few"miles from where the actual meetings are held, but it's a best approximation as most grottos do not list addresses for their meetings on the nssio website.
As an example of the coolness these files will bestow upon you, try overlaying your points over a geological map of the US. Now you know which grottos are closest to your favorite geology. (Geology map not included :p)
If you click on the picture above, (or squint) you can see I've highlighted my current home grotto, the Triangle Troglodytes. Unfortunately not very close to caves :'( The lack of proximity to caves further adds to my two persistent problems with going caving. Knowing where caves are located, and having people to get underground with. Someone recently suggested I swing by the VPI grotto while living here, but before doing this project I didn't know where in Virginia they were. Granted I could have googled the individual grotto, but then I wouldn't have known about all the other organizations nearby. This project has made that much easier.
Download the KMZ