The people over at the Princeton’s Witherspoon Institute have a new website, Natural Law, Natural Rights, and American Constitutionalism, which houses a number of online articles concerning natural law. Here’s a Thomist-centric culling of some of the articles and authors (many other articles are there as well!):

Aristotle, Natural Law, and the Founders
Michael Pakaluk, Ave Maria University
Aquinas’s Theory of Natural Law
Thomas D. D’Andrea, University of Cambridge
Ockham to Hooker: Late Medieval Transformations of Natural Law
Paul E. Sigmund, Princeton University
New Natural Law Theory
Christopher O. Tollefsen, University of South Carolina

Many of these on-line articles have PDFs as well.