I use one of these click here It connects to my router by ethernet cable and provides four USB ports. I then have two external drives and two printers connected to it, which are available to any computer in my network (although not simultaneously). To the PCs, the devices appear as though they are connected directly to one of its USB ports.
This arrangement does, of course, limit the data transfer speed to the 100Mbps of a wired LAN. If you are proposing to use 802.11g (54Mbps) wireless connections, you'll be lucky in practice to get 30Mbps. An 802.11n wireless connection at 300Mbps should be comparable to a wired 100Mbps LAN but performance will inevitably be poorer than if the drive were to be connected directly to a USB 2.0 port running at 480Mbps.