As a chef married to a technology geek, I benefit from finding out about a lot of cool stuff that comes out on the web and otherwise.
One of my favorite things on the web, especially in determining nutritional value and doing conversions is Stephen Wolfram's http://www.wolframalpha.com
I often use this professionally to get nutritional information on recipes I've created and thought a lot of people may not know about it, so why not post it here.
It can do other cool shit, so look at the examples. I've been amazed. In fact, my friend (an early adopter) has the new iPhone that has Siri on it and you can simply ask it a question and it uses the wolfram engine to convert it back to you in a robot voice. Lazy, I know, I love math too, but there are moment in the kitchen when rationality has completely left the building and I think its perfect for that.
Let me know what you think.