Motherlode

Whole hunks of the Paul Krugman/Robin Wells microeconomics/macroeconomics textbook is posted online here:

http://www.pkarchive.org/theory/13.html

(This seems to be an early '00s edition.)

I've just started browsing macroeconomics, which begins at Chapter 6.

EDIT: And there are chapters here, too (some overlap):

http://www.worthpublishers.com/krugmanwellsnew/samplechapters.htm