Are you familiar with it ?
I have signed up for a frappr listing on several web sites.
It is cool to know where those names you see on the forums all the time are actually located at.
Example: if our association had a frappr link listed in these forums, a cacher could look in a area they had plans to go caching in, to see who they know there.
Other use, list a cell number in case you have a flat somewhere way out and your spare has gone flat.
Or, your zebra GEO takes a mud bath and you can't get it out by yourself.
The local authorities may not be GPS equipped in order to be able to find you. But you would have the cell numbers of local cachers that would be glad to help you out.
For more information about how FRAPPR works click on this link:
I am listed as "mountainborn", and I show no phone number, but would for an Arkansas Geocachers Association FRAPPR listing.