A lot of non-graphical utilities — basically the *NIX coreutils, plus stuff like rsync, ssh, compression/archival tools (tar, gzip, bzip2, etc.), grep, and the like. Git also comes to mind.

I think part of this is that the UNIX philosophy is “developer friendly” — tell a good dev they need to make a compression utility that follows this protocol, and they will make a compression utility that follows the protocol.