A 531 weightlifting program calculator written in ruby.
In the text file Lift_nums.json open and add your current 1 rep max as per Jim's instructions for each lift. Then simply call the program and you should be good to go. If you ever need to adjust your lift values you can simply choose "press" and week "4" when running the program and it will accept either positive or negative values when asking for how you want to change your lifts. So if you tell it to change by "-5" it will decrement the lift in question by 5, "5" and it will increment by 5.
Link to the 531 Program book (non affiliate, I just like the program)
http://www.amazon.com/Simplest-Effective-Training-Strength-Edition/dp/B00686OYGQ