Interfacing 8051 with Android Phone


I want to make an android phone application to get data from the 8051 microcontroller ,so what is the best and easiest way to do that ?

I've heard about Xbee and IOIO , can I use them ? , what do you suggest ?

thank you,

Bluetooth serial module connected to the 8051 serial port? For software, you're probably on your own.

can I use USB cable to transfer data between the microcontroller and the mobile phone