If the problem is battery life, and not gadget functionality, and you're willing to carry a second box ... why not carry an external battery charging device, like a Tekkeon or U2o? The Tekkeon MP3450 is only a little bit bigger than carrying a 2nd device, you only need to carry it when you're worried about power, can easily hide it in a gadget bag if you carry one, and it has adapters (some included in the base unit) for all of the listed devices. The MP3450i has a different set of included adapters, but I don't think it has support for USB charged devices ... and there are some other devices in that series that might apply as well. Smaller than but without the HUGE expansion in power, is the Tekkeon TekCharge MP1800, which includes chargers for NITs, and has optional adapters for things like PSP, Garmin, Nintendo... and can charge USB devices (like HTC phones). I'd much rather carry an external battery for a heavily used device than carry multiple devices. (my other strategy is that I make sure I have not only a charger in my gadget bag, but a charger at work and at home ... so I don't need to keep winding and unwinding chargers at my common locations, only when I'm at non-usual places)
They're maemo and MeeGo... "Meamo!" sounds like what Zorro would say to catherine zeta jones... after she slaps him for looking at her dirtily...