Hi,
I'd like to have a play with a powerbank UPS setup as described here http://raspi-ups.appspot.com/en/index.jsp, There is some local discussion here.
I'm after recommendations for locally available USB powerbanks that have passthrough *and* continuous power output. Many powerbank devices that have the passthrough capability (outputs power while the charging input is connected) will momentarily drop or disconnect the output voltage when the charging input is disconnected, causing the powered device (RPi, Arduino, etc) to reset. For example Jaycar's MB3796 and MB3797 have this issue.
The ideal device would also run some sort of UPS comms protocol over the output USB connection so the attached device could read the battery level, etc. I expect that it's highly unlikely that any of these devices will have that feature, but you never know unless you ask.
I realise that a 12V SLA and 5v regulator is probably a better solution, but that requires more components and some construction. The powerbank method is so simple and, if you are not concerned about sensing when the mains goes off, only requires USB cables.
Glenn