FSF's Chart of Doom
Tom Callaway had to rant, knowing it's a rant, but he needed to get it off his chest. FSF's own licenses are so trickily compatible-and-less-than-compatible which each other, that the compatibility Chart of Doom is just horrendous.
Dual license for all the files in the package, Multiple files with different licenses in the same package, Multiple files with different licenses in the same package, and some of those files are dual licensed... what a nightmare! (Different licenses can mean: "GPLv2 or later" and "GPLv2".)
Also: Free Software Licensing, Part 2: Beyond GPL @ Linux Insider.