I've thought about the possibilities of using GPS and air data along
with a well-stocked GIS to advise a pilot of the better places to
ditch. Using aircraft performance, wind, and terrain elevation
data, it would be fairly easy to determine the areas that could be
reached if power was lost. The terrain data (slope) would also be
helpful in determining which areas are poorly-suited for an
off-airport landing.

I recently came across some land use data for North America.
http://nationalatlas.gov/landcvm.html
It struck me that it would be handy to mix that into the equation.
For example, I think I'd choose "Dryland Cropland and Pasture"
over "Evergreen Needleleaf Forest" over "Urban and Built-Up Land"
if I lost power at night (with the terrain slopes all the same).

I recall that someone did a study of water vs. forest ditchings
awhile ago. Anyone know if there's research on the safety of
ditching on different types of land? Hmmm...I wonder if I could
get funded for a bunch of C-182s...

--kyler