I always thought it'd be cool if all programs implemented external apis this way. Kind of like how applescript works, but, for a mail program, for instance, write "Hacker News" to /proc/n/query and it'd return the data. Or write 'message 1' to /proc/n/open and it'd open or return it.
You wouldn't put those sorts of things in /proc, but that's basically how things work. And since it's a filesystem, you can export your API effortlessly over the network.
