Most of the routers that lie on stores shelves are really little PCs: most of them contain small amounts of RAM, CPUs, and a small amount of storage. That means it's possible to run whole operating systems on them, bringing the possibilities of Linux to the little box that used to mindlessly serve data around your network. A hack that adds a USB port to a router is now getting the attention it deserves: using a Sweex LB000021 (a dead cheap router that goes for around $40) with flashed firmware, it's possible to solder on a USB port and hook up USB devices like portable flash drives, and potentially printers. Those kind of features tend to be exclusive to relatively high priced consumer routers, so it's nice to see that those competent with a soldering iron can cut a few corners and get similar features for much less. Just make sure you check and see that smoke doesn't come out of anything when you switch it on: "that's not what it's supposed to do," apparently.