Emissions trading, in which a developer pays a fee in order to ensure environmental protections in sensitive land that it owns, and in return receives rights to develop land it may own in much more development-friendly areas, has only been an idea for about 25 years. Except for two things. One, the practice is now referred to as "fee and trade". Two, Maryland now is apparently interested in doing it.
Yay for the home team! You can read a little bit more about this interesting development scheme here.
The article is a little bit technical and geeky in describing the system, but I love it. Anything that encourages-- dare I say forces?-- development more (or back) into areas that already contain the infrastructure to sustain the resulting capacity is a good thing by me.