AllFlashFiles.com is a good community website that provides all mobile phones flash files download. Here they provide downloads of all major and minor firmwares for flashing of Nokia, Samsung, China mobile phones. Also they give all the guides and tips on how to do flashing and formatting of cell phones.
They also give flashing tutorials for flashing with various flasher boxes and softwares like UFS Micro(HWK), Volcano, Piranha, Z3X, ATF Box, etc