These are some of my most frequented sites. I'll break them down into fitness/nutrition related and then everything else... (in no particular order)
Leading the Way - My sister-in-law's Weight Watchers based website (old POINTS system). She lost an amazing 80 pounds and has kept it off for over 9 years now. She used to be a WW leader and in fact, was named Rookie Leader of the Year her first year on the job. This is a great resource for recipes, calendars, and motivation. Check it out!
Map My Run - I use this almost every time I run outdoors. It's a good tool for calculating how far you are running (or walking, or biking, etc). Once you sign up for an account, you can save any of your run routes to look at for future reference.
Fat Secret - This is the companion website for the calorie counter app I have on my Android phone. I love the app. You can find my review of it here. You can sync it up with your online profile as well as find recipes, challenges, forums, etc.
Jeff Galloway's website - He is a strong proponent of run/walk pacing, especially for long runs. But he has great, sound advice for all levels of runners. It's from his half-marathon training schedule that I created mine.
John Bingham's website - he is very inspirational for all of us "Backpackers" (those of us who run in the back of the pack during a race and only glory in finishing, not in setting new land speed records.
Run With Paula - Paula Harkin's website for local events associated with the Portland Running Co. She also has a blog listed there and info on the training groups she works with.
Road Runner Sports - For all running/triathalon gear. The even have nutrition bars, gels, etc.
One More Mile - They offer great motivational tech shirts and other gear, including stuff with John Bingham's "Waddle On" penguin logo.
Allied Medal Displays - Proudly display your running bling! AMD will gladly make a custom display for you if you'd like.
Road ID - Get all of your emergency contact information and medical information on one convenient ID tag. Mine has my ICE contact numbers as well as my drug allergies. I don't run without it.
Jody's Vault - My eBay resale store. Check out my workout wear as well as other good finds in resale clothing & other item.s
Audible - I listen to books that I download as I run. I can't stand it when music changes tempo during runs and listening to books lets me set my own pace.