Takings law is a greatly misunderstood area of growth management. This page is a very good primer on the issue and should help planners to understand just where the "line" is drawn.

http://sac.uky.edu/~jdlong00/takings.html

Here are a couple more links to some publications from the University of Kentucky College of Agriculture that are relevant to planning.

http://www.ca.uky.edu/snarl/landusefiles/landusepubs.htm

http://www.ca.uky.edu/snarl/communityresourcefiles/communityresourcepubs.htm

"Best Practices" site has some interesting samples of regulatory tools from across the US. These two sites offer several examples of different regulations for specific problems.

http://www.nga.org/center/divisions/1,1188,C_ISSUE_BRIEF^D_2495,00.html

http://www.aloha.net/~inazoo/model.htm