If you have flashed a custom ROM to your Samsung Galaxy S phones in the past then you must know of ODIN software which allows you to install third party firmwares without going through the official way. Now a new application Mobile Odin has been developed by Chainfire from XDA forums which allows you to do the same stuff directly on mobile device, the only requirement is that your phone must be rooted for this to be able to work. A free and paid version is available, links below.
Download Mobile Odin v1.1 APK
Mobile Odin Lite version download from Official XDA Thread
Download Mobile Odin Pro from Market.
Mobile Odin Pro Desktop link.