Network protocol fuzzing
There have been some projects to use the AFL engine to do network-protocol fuzzing, in addition to file-format fuzzing. I haven't looked into them in a while. It'd be interesting to see how much work it would take to adapt AFLSmart to that sort of use.
Of course, you can always create client and server drivers that use an input file to generate the network traffic, and fuzz that. Or stub out your networking logic with equivalent file I/O. But having builtin network capability would be useful.
I remember when Zalewski first made afl-fuzz (the original American Fuzzy Lop command-line fuzzer) public - I think I have the email archived somewhere in one of those "take a look at this" collections. It's hard to believe that (according to the CHANGES file) it's only been five years. Lots of bugs have been found by it in that time.