I have been tasked with capturing the Business Rules in an legacy program that my company uses a lot.
As I was about to start, I fired up Excel and started typing. It took only a very short time to realize that it would be better if there were a customized tool to enter this information into.
This is a new task for me, so I don't know if I am hoping for software that is either non-existent or is expensive. But I figured it can't hurt to ask if anyone out there knows of a nice free tool to enter business rules into.
Depending on how complex the business rules are you could you a flow charting app like Visio. If the rules are numerous and complex your diagram might get large or have to span several pages to be readily consumable by persons other than yourself (page object links work well for this case.)
I have produced charts like these that have spanned up to 20 printed pages (4x5) with many dozens of objects and decision points. The end result, though large, is very useful because the non-tech, biz-types can follow along, help make decisions and programming the biz logic from the chart becomes almost trivial.