The Principles of Political Economy
The Principles of Political Economy by J.S. Mill
http://www.socsci.mcmaster.ca/~econ/ugcm/3ll3/mill/prin/

Evolutionary Economics and the Counterfactual Threat
on-line article by Robin Cowan and Dominique Foray
http://www.cgl.uwaterloo.ca/~racowan/counter.html

Genetic Causation and Economic Theory
on-line article by Robin Cowan and Mario J. Rizzo
http://www.cgl.uwaterloo.ca/~racowan/cause.html

History of Economic Thought Archive
Includes both primary texts, studies of those texts and of their authors
http://socserv.mcmaster.ca/econ/ugcm/3ll3/

Could There Be a Science of Economics?
on-line article by John Dupre
http://cogprints.org/347/