File Systems
Open-Source File Systems
FatFs
URL: http://elm-chan.org/fsw/ff/00index_e.html
A generic file-system module designed for embedded systems which supports a Windows-compatible FAT file structure. It is written in compliance with ANSI C and is separated from the disk I/O layer, therefore is independent of hardware. Supports RTOS (i.e. supports threading/tasks).
Sample projects exists (with the driver layer written) for AVR, PIC, Win32, and a number of other architectures.