You can add the even-cooler-stuff as another remote repo(like origin) and grab those changes and branch off of one of is branches then you can make pull requests to even cooler stuff from those branches.
https://stackoverflow.com/questions/7244321/how-do-i-update-or-sync-a-forked-repository-on-github
I'm pretty confident the reason GitHub isn't allowing you to fork the even-cooler-stuff repo is that technically they are the same repo... And multiple remotes should do the trick.