I found the Member Map versions that have been used here to be helpful but it depended upon each and every user dropping a PIN on their location. It also would not allow the Member to delete or remove a PIN if it was dropped in the wrong place, or if the Member moved.
Ultimately, a COST/BENEFIT analysis - even if superficial and non-scientific - would most probably fail to justify hosting expenses.
One "dream feature" I have often fantasized about would be what I describe as a MAYDAY FUNCTION. Much like a 911 call, or an SOS signal, a distressed Member could post a short MAYDAY message to the MEMBER MAP (or a companion WIDGET) and the system would automatically PM, EMail, AND Text to the geographically nearest 100 MEMBERS (or more as determined in practicality) regardless of distance from the MAYDAY. This "broadcast by the numbers" would inherently adjust the range of MAYDAY's broadcast for that locale's Member density factor.... Where there are lots of Members, the radius would be tighter and conversely, where Members are few and far between the broadcast radius would be larger to accumulate the set number of recipients. I would actually prefer a greater number of recipients be used, but I also realize that dang cost/benefit thing has to be considered too.
Just as with the 911 System, I would recommend STIFF PENALTIES for FALSE ALARMS. A true DISTRESS SITUATION might be roadside emergencies, vehicle collisions, and the incapacitation of a Member (secondary to an actual 911 Call) so that other Members could secure an "abandoned" MV. Considering the family ties of our Membership, I would even endorse allowing non-MV (or POV) distress calls to use the MAYDAY System.
Another useful function would be "Route Planning". By this I envision being able to map your anticipated route and from that the Member Map data base could generate a contact list of those Members (with their capabilities??) who are reasonably along your travel path. Secondarily, it could be used to notify those along your route (similarly by PM, EMail, and Text) of your trip specifics such as itinerary, type of vehicle, and "souls on board".
But alas!
These ideas just won't fly without FUNDING. Though we can still dream, can't we???