Somebody we know wrote a whole book dealing with this stuff.
There are some great threads on FR as well.
BIG GREEN : Inside the Nature Conservancy Nonprofit Land Bank Amasses Billions
Environmentalists Organizations Exposed
And my personal favorite, please pay attention to the wonderful posts by our own Carry_Okie who has some wonderful photographic "evidence" on this thread.
Water rights fight--farmer regrets selling to an open space trust