This is from Building Science Corp. and some of this material has been linked other places on the forum.
This is a good review of "best practice" building based on the all-important climate characteristics.
http://www.buildingscience.com/housesthatwork/default.htm
And here is tonights Top 10... http://www.buildingscience.com/topten/default.htm
Here is another link, a PDF file, on how to build conditioned crawlspaces: http://www.southface.org/web/resources&services/publications/technical_bulletins/CI-Crawlspace%2000-774.pdf