There are several approaches that use a mix of tools, often that work in conjunction with eachother. I don't want to spill what I know about the topic, because I don't have the time for it. But I would suggest reading the following.
Saved by Development - Rick Pruetz (foremost expert in TDR's)
Holding Our Ground - Tom Daniels and Deborah Bowers (Tom's work is excellent)
When City and Country Collide - Tom again.
Protecting Farmland, What Works? - The American Farmland Trust (if you become a member of the AFT, you get a copy of this excellent book).
One of the best examples (and believe me there are plenty out there) is Lancaster County, Pennsylvania, where Tom Daniels was instrumental in preserving farmland and curbing sprawl. There are numerous articles on the Lancaster County model.