$55 item 131 0949 USB over CAT5 Extender W/ 4-pt Hub, Extends To 150ft
I've used one with multiple USB 1.1 devices and it seems to work fine.
First application for me is to move the INSTEON USB 2414U interface/controller to the Powerline Playground near the AC entrance panel where the X-10 CM11a used to bewhile leaving the HA PC controller where _it's_ supposed to be. (The INSTEON 2414S RS-232 interface/controller is still problematic under HomeSeer in my experience.)
These USB extenders will also allow me to move PC's to the basement -- where they will be more secure, quieter and run cooler -- but still have keyboards, mice, webcams w/ mics, etc. And fewer PC's will be needed. This presumes that one can/has run ample CAT5 ... Prices and performance of DVI- and nVGA-over CAT5 are improving also but still more expensive than analog XVGA splitter-amp + high-quality analog cables.
Reasonably prices USB 2.0 extenders ($22 item 131 0891 from cyberguys and other places) still seem limited to 16 feet. I've used two in series OK. ABIK, USB 2.0 over CAT5 for longer distances still costs $hundreds.
HTH ... Marc