• 1. Introduction
• 2. Galaxy rotation problem
• 3. Other indications of Dark Matter
• 4. Potential explanations

Dark Matter: 5. Further Reading

• up to Universe

Elsewhere on the web

• Wikipedia: Dark Matter
• Dark Matter Guide from the Chandra X-Ray Observatory
• The Nature of Dark Matter from NASA's Imagine the Universe

Books

• Dark Side of the Universe: Dark Matter, Dark Energy, and the Fate of the Cosmos by Iain Nicolson (2007)

Videos

• Mysteries of the Dark Universe (2009 Buhl Lecture at Carnegie Mellon University by Edward Kolb from Chicago University). There is also a version of this lecture on Apple's iTunes.
• The Dark Matter Mystery (five minutes, from PBS' NOVA ScienceNOW) covers the evidence from the Bullet Cluster collision

Review articles

• Dark Matter (arXiv:0901.0632 by J. Einasto)
• Dark Matter Search Experiments (PDF of lectures by A. Lindner in July 2011)