I use http://www.physicsdiet.com
to log my weight every day.
...which is based on The Hacker's Diet, an e-book that I absolutely adore: http://www.fourmilab.ch/hackdiet/e4/
I currently use http://www.livestrong.com/thedailyplate
for tracking my calories... I like some things about it... I've never found a calorie tracking site that I really love
I get most of my recipes from http://recipezaar.com
- it's fairly easy to search for low-fat, high-protein, low-carb, whatever you need.
I also find a lot of healthy recipes on Martha Stewart's website, especially her "Whole Living" site: http://www.wholeliving.com/