canon NB-5L Battery pack shell
This shell makes it possible to wire out a external supply.
I've tested the fit, but haven't finished the construction.
use a supply like this http://www.pololu.com/catalog/product/2101
wire it out to a wall wort, or a larger battery.
use http://chdk.wikia.com/wiki/CHDK to set up a motion sensitive HD security cam
add a Eye-Fi card for remote network upload.