Last summer I was trying to locate a site away from town with dark skies. Of course, just having dark skies isn't really enough -- it also has to be accessible by car. To satisfy these dual requirements I wrote a page that couples Google Maps to data supplied by the International Dark-Sky Association to produce the "Dark Sky Finder" utility:
Take a look and enjoy! I would like to see this utility improved & more widely used, but I don't have the time to do it justice. I have contacted the IDA in an attempt to transfer it to them for better publicity & coding support. If any astronomically-oriented web developers are reading this and would like to continue with this project, please let me know! I am always willing to just GPL what I've done so far & put it on SourceForge (or some such thing) if there is interest, but I don't want to bother setting up a SourceForge project if it would not be used.