Linear has these great little supercap chargers, like LTC3625 and LTC4425. These are intended to take power from weak source and charge a pair of supercaps, with cells balanced, to provide high peak output power.
I am thinking of getting a few+ some caps to play with, but it would be really great if there was a prepopulated PCB as these are all SMT chips.
Unfortunately all these are designed for 5V (2 capacitor in series ) output apps, i have not seen a simple solution yet for doing a 4 or 6 in series higher voltage app - this would require quite a bit of external circuitry to balance the cells.
LTC has all the ref app notes on their website, such as this backup power circuit http://cds.linear.com/docs/Design%20Note/dn485f.pdf
EDIT: actually, i just found TI BQ33100 which can manage up to 5 cells, so like 15 volts. $10 chip though.