I wanted to post this in the gearmaking thread to keep this from fading away. Here is a geared iphone cover that works! Lets get this discussion of gearmaking back on track
http://www.instructables.com/id/IPho...for-Engineers/
all the associated files in stl format are included...
http://grabcad.com/search/library?query=gears
http://grabcad.com has a ton of free files, not only gears.