Perhaps a universal charger that charges Lithium Ion and NiMh and NiCd AA and AAA might be useful such as the Ansmann Digicharger Plus

http://www.adorama.com/ANDGP.html

A lot of gadgets with dedicated Lithium Ion cells usually have the recharging circuit built into the device and many of those gadgets just need a DC-DC universal regulator i.e. 12V cigar connector to whatever the DC Voltage requirement of the gadget is designed for. Many of these gadgets are also more compact and lighter than their AA or AAA NiMh equivalents.

Is there such a thing as an AA powered mobile phone?