A friends on one of my email lists sent the link to this site and I've just spent about an hour playing with it. It has nutrition facts for all kinds of food in a searchable database. It has a tool that you can use to analyze your recipes. Like any other nutritional/diet site I'll take some of te advice with a grain or two of salt, but it is really cool to be able to do the nutritional anaysis.
It also had a plug-in for my Firefox. (If you aren't using Firefox you're missing out!)