Running LMS on a tiny server

If I wanted to run LMS on a tiny system, what would my choices be for that system?

I already have display/keyboard/mouse and USB external drive, so I need a system unit and some form of WiFi access point.

I've seen tiny systems about the size of a paperback book in the past, but they're not so easy to find now.

Or how about a router that allows you to plug in a USB drive, and add applications of your own choice? Could I get LMS running on a router?