Internet resources regarding Dark Matter can sometimes be difficult to filter - meaning that a few discuss some pretty outrageous theories. Some of the more "reliable" links are below:

• Astronomy Department at Princeton University
• Max-Planck Institute
• LSST Observatory
• Galactic Rotation Curves
• University of Tennessee - Dark Matter Summary
• DAMA

Computer simulations are vital in Cosmology:

• Astrophysics Source Code Library
• N-Body simulations
• N-Body Method Resource
• Astronomy.Designerz.com - I wonder if their web designer also does spell checks on spam?

Galaxy Related Websites:

• Inter-Stellar Medium Molecules
• Logarithmic Maps of the Universe
• Parke's 21cm Multibeam Project
• Taurus Tunable Filter
• Hubble Deep Field South
• The Antennae - NGC 4038/39
• The SKA - Square Kilometer Array
• NGC/IC Project
• NED - NASA/IPAC Extragalactic Database
• Galaxy Zoo

Cosmology Related Websites:

• The Gravity Probe B Mission - testing Einstein's theory of Frame Dragging
• Cambridge Cosmology - Lots of cool stuff
• BOOMERANG - maps of the Cosmic Microwave Background
• Planck Science Team Home - the next generation CMB probe
• UCSB Astrophysics Project - cool stuff happening in Santa Barbara
• UCSB Experimental Cosmology

High Energy Astrophysics and Particle Physics Resource List:

• The ABC's of Nuclear Science
• The Particle Adventure
• SLAC Virtual Visitor Center
• CERN
• SOHO
• NASA's Cosmicopia
• Super-Kamiokande Detector
• The Ultimate Neutrino Page
• Neutrino History
• Chandra X-Ray Sources
• NASA's Imagine the Universe
• BASTE Gamma-Ray Astronomy
• Dark Matter
• The MACHO Project
• Test of Warped Space
• Michael Murphy Research - Variable Fundamental Constants?
• The Higgs Boson
• Super-Kamiokande
• String Theory
• The Soudan Underground Laboratory
• Atomic Physics Online
• All About Nuclear Energy and Radiation