Softwares, Calculators....

[TheWizard]

FilterPro™ Multiple Feedback (MFB) and Sallen-Key Design Program is a Windows application.......
http://focus.ti.com/docs/toolsw/fold...filterpro.html

Some Calculators and Other Utilities....
http://focus.ti.com/adc/docs/midleve...ontentId=23657