I’ve used this program in the past to build a recipe and I’ve always liked it, they’ve added tools so I think I’m going to start using it again. I like that it calculates the calories too, just for the sake of curiosity. 8)
I have used it when I was at work and didn’t have access to Promash. It’s pretty cool, but adding everything with drop-down menus seems a little difficult (to me anyway).
I will say that it’s a well-designed website.
The only thing I don’t like about it is with every addition you make it has to reload, so if you’re using dialup internet it can be slow. 
My biggest complaint is that you can’t see the potential extract or color of the grains until you add them to a recipe. So you can’t make a quick estimation to get the gravity and/or color contribution you want; I generally have to revise the quantity at least once or twice. It is very well laid-out, slick and fast.
I tried that one, but I like this one better: http://buildabeer.org/ It doesn’t have the reload delay, shows style guidelines as ranges, and has nice links to the BJCP style guideline descriptions.
Hey thats a good one too, thanks yugamrap. 
Oh I likes It! Will definitely use it from now on.
This is a nice simple calculator: http://tastybrew.com/calculators/recipe.html