A flash file system is the way in which an entity of data (file) is named and where it is placed logically for storage and retrieval on a NAND-based solid state storage device.
A flash file system cannot be accessed by the end user. It is built into the firmware and is used by the flash controller to manage program/erase (P/E) cycles on the flash media. Flash file systems, such as a NAND flash file system, are generally proprietary and specific to individual flash controllers.
Unsorted Block Image File System (UBIFS) – http://www.linux-mtd.infradead.org/doc/ubifs.html
Yet Another Flash File System (YAFFS) -- http://www.yaffs.net/