I've been experimenting with hub and power options. A possible battery-powered hub is the CyberPower CPH420MP. However, it has mixed reviews; may be out of production; and has AAA batteries, so would last only a couple of hours or so supplying a USB2VGA2 at ~500 mA. The benefit is that it combines power with hub, of course.

An alternative is to couple a tiny hub, like the 4-port Targus ACH63EU (also sold as Synapsis by Maplin) with a decent battery. The USB Battery Pack (GBP 16.50) is compact and will last about 6 hours at 500 mA (max output 700 mA). It comes with stick-on Velcro, so you can mount the hub on the battery (it helps to have some little stick-on feet as well). There's a beefier battery from Bixnet.com (~53 hours @ 500 mA; max o/p 1,500 mA), but it costs USD 79.95.

Stacked together with Velcro, feet and customised wiring connectors, the USBVGA2 + battery + hub looks quite neat:



For use with a projector (which has AC, of course), there is the opportunity to use a 5V power-supply, but I don't want the clumsiness of a separate AC plug. There is a nice in-line 5V supply from Lindy (GBP 29.50 - probably there are cheaper alternatives), which sits nicely on Velcro at the back of my projector (Optima EX530) and I use a Y-cable to supply it and the projector:



Here is the complete set-up, using a micro-A(M) to USB A(F) adapter and a nice long USB A to mini-B cable. The jpegs are on a micro SD card on the dongle plugged into the hub - very handy. I sometimes plug a USB keyboard into the hub as well. The picture on the wall is being projected!