I found this site today. 4th order IIR and 21 tap FIRs are free. You have to pay for more.

http://www.micromodeler.com/dsp/

Here's their introduction video:

 

In PSOC Creator, free, is a tool for FIR to 128 taps, IIR, BiQuad Cascade, free, produces coefficients.
Choose PSOC 5LP when starting a new project, and drop DFB block onto schematic, then double
click it, config, you are in the tool.

http://www.cypress.com/products/psoc-creator-integrated-design-environment-ide



Regards, Dana.