Bummer that you're busy DiegoFrogs, I'm very much not so presently.

I've put together a simple spreadsheet that shows chainlength using the formula shown above (which is equivalent to Park's "rigorous" equation). It calculates gear inches as well.

I'd like to add a few more tabs for specific items, like finding whether you can chose a gearing to get near a certain gear ratio on vertical drops and what kind of gearing choices you can make for a flip-flop hub. However, if anyone wants to take a look at this and give me some feedback, PM me.