National Bureau of Economic Research (NBER) Working Papers
NBER working papers are available on-line here; this includes all papers submitted since 1994. This service is freely available to subscribers of the hard copy series (individual papers can be purchased). It is also freely available to computers in non-OPEC or non-OECD countries (this is determined by the "top-level-domain" of the computer, and "reverse name-lookup" must be functioning). The entire National Bureau of Economic Research (NBER) site is described elsewhere in this guide.