This page collects some useful resources for working with Windows Phones.
WPInternals by an XDA-User allows you to perform tasks like unlocking bootloaders, enabling root access and flash or backup firmware.
Windows Device Recovery Tool
The Windows Device Recovery Tool by Microsoft let you recover firmware of Windows devices.
Android4Lumia is a project which aims to built android based custom roms for Lumia phones.
On LumiaFirmware.com you can find firmware for Lumia Phones.