The Friedman equation . Overview of the terms in the equation, with an interactive Java applet to plot solutions. A discussion of frequent misconceptions in cosmology, by both beginning students and textbooks. Textbooks An Introduction to Modern Cosmology by Andrew Liddle.
Web page contains links to errata and recent developments.
Cosmology, 3rd Edition by Michael Rowan-Robinson. The home page for MRR's cosmology course at Imperial College includes a few errata. A home page for the book seems to be under construction. Cosmological Physics by John Peacock. Errata, plus some updated figures.