FTDI encourages progression of the Android Open Accessories initiative, with FT311D host IC targeted at connectng Android platforms (tablet PCs, smartphones) to other systems through USB. Running off a standard 3.3V supply and drawing a current of just 25mA in full operation at 48MHz and 128µA while in standby mode, the FT311D has the capacity to bridge the USB port to six different user selectable interface types.
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT311D.pdf