I'm not sure what you are looking for.
But you might look at the stickies in the 'Taxes' forum.
There is also FIRECalc and cFiresim.
MDM has his CSS, Case Study Sheet which is really good for tax planning, but I think there is a lot more in it, I just didn't that while using the CSS.
If these don't fill your need, try more explanation about what you are looking form.