#1 Homebrewing Digital Book, We strongly recommend you take a look
BeerSmith makes creating your own beer recipes easy. It allows you to define the hops, hops schedule, malts, specialty grains, etc. and will calculate various different values, such as IBU, SG, ABV, and many others.
For the intermediate level brewer, looking to try his or her hand at creating their own beer recipes, and keep them within the appropriate styles and such, or expert brewing looking for a better recipe solution, you can't go wrong with this inexpensive yet very powerful brewing tool.