www.randi.org - The James Randi Educational Foundation
www.whatstheharm.net - Excellent resource for when someone asks 'What's the harm?' when discussing nonsense ranging from ear candling to reiki.
www.sciencebasedmedicine.org - Excellent blog by doctors and scientists about medicine and quackery.
www.quackwatch.com - A website with a seemingly unlimited amount of information about quackery.
www.blogs.discovermagazine.com/badastronomy/ - The Bad Astronomy Blog by astronomer Phil Plait about astronomy and the pseudoscience that often hangs onto its coattails.
www.skepdic.com - The Skeptic's Dictionary. Just like it sounds.
www.sciencedaily.com - Science Daily - all the latest science news; just pick your topic.