Anybody got any ideas on how to replace this invaluable source? I
thought
about setting up a Wiki-like site where people could edit and enter
data
for their part of the world, and then have the data available in an
architecture neutral format (like maybe an extended GPX xml schema),
but
I'm not sure I have the time to implement such an idea on my own, and
I'm
not convinced that anybody would actually use it.

The developers over at pocketfms.com are working on a volunteer-based
system where people type their local airport data into Excel charts..