Quite interesting news: I was searching for a battery suitable for my Beagleboard xM... and I found this supreme rating BixPower BX550:
* 5V output, up to 3 amps continuous output (wow!)
* 49 W/h total capacity
* 12V charging current (at least 1A, I suppose)
The Beagleboard xM, in extreme conditions (everything switched on, processor on full throttle, and full 500mA peripherals on all four USB ports), requires something less than 3 amps at 5V. Yay! This is a "must have" for heavy Beagleboard usage and for all "hungry" 5V projects.
Size and weight are reasonable:
* 153mm x 93mm, 23mm height
* 418 grams
23mm height is not far from what an "operative" Beagleboard xM could require.
If I think some medium consumption of some 5V1A (this could be a decent figure even if you have 4 USB devices requiring 500mA each but on a low duty cycle), I bet that battery could last 8 to 9 hours. Double that value for a Beagleboard C4 without USB peripherals.
Good: packaging includes a DC car adapter.
Good: the battery has 4 LEDs for charge status (25-50-75-100%).
The only thing disappointing me (but not normal users) is the absence of the classic basic protections: "battery too low" protection (BixPower requires to start charging before the battery is exhausted), "reverse polarity", "overcharge".
UPDATE! UPDATE!! As of June 2011, the BX550 has all protections: over-charge, over-discharge, over-current, short-circuit. GOOD!!!
Anyway, not only I strongly recommend it... I just want to buy at least a pair of them as soon as the BixPower makes them available!