Brewtarget is a free and open source application for Windows, Mac, and Linux that helps you get the ratios right as you formulate your homebrew recipes. Check the video:
http://www.youtube.com/watch?v=qh4GWI_EUxE
It uses BeerXML, making it compatible with BeerSmith.
Brewtarget (Sourceforge)
(via Lifehacker)
