I like seeing PHP get used outside of the LAMP stack and web applications. That’s because PHP works well in lots of other contexts as well. There’s been a web server written *in* PHP for a while. And, it looks like there’s now an FTP server written in PHP as well.

I’m not saying you should drop proftpd and switch, but it it’s definitely an option. And, if you go digging though the code, it serves as a pretty good example of how to write a server application. So, when it’s time to write your own custom server, you’ve got a good example to work off of.