Got my STM32F4DISCOVERY board today from digikey. I didnt know there was a cortex-m with an fpu so I wanted to try it out. Cost about $20, they are giving these things away you might as well get one.
Customizable Bootloader for STM32 microcontrollers. This project includes demonstrations for various hardware how to perform in-application-programming of a firmware located on external SD card with FAT32 file system.