Ok Makers, here's a portable graphical resistance calculator for iPhones, but it should work on most other things including most/all computers too, enjoy - Link.
Try it out, if there are any changes to make it look better just send me a HTML file and I'll upload a new version (just keep the credits from the original author in there).
http://blog.makezine.com/archive/2008/01/graphical_resistance_calc.html