Docerator

docerator automatically creates Mac OS X document icons given an application icon and one or several file extensions.

It is a tool for application authors that don't have the time or the money to create a docicon, but already have an application icon. It's also useful if you need to create many document icons.

docerator takes some care to create great-looking docicons at all sizes: The text on the 32x32 icons generated by docerator is readable, which is not the case if you draw a 512x512 doc icon and then drop this on Icon Composer to create all variants