Chainfire's abilities know no bounds.  The XDA Moderator and Recognized Developer now presents Mobile ODIN, allowing you to flash firmware from your device, itself.  That's right, you no longer need to connect your device to your computer.

All right, that's not perfectly true--Mobile ODIN currently cannot flash PIT, bootloader, or EFS partitions.  You still need your computer for those.  For now.  But if you want to flash a new kernel, system, DBData, data, cache, parameter, or modem partition, Mobile ODIN can do that.  As the developer says,

All partitions are supported, as are loose files, .tar files and .tar.md5 files. Mobile ODIN will even check the MD5 signatures before flashing. While in theory Mobile ODIN can repartition and flash EFS and bootloaders, it will cowardly refuse to do so, for your own safety.

Mobile ODIN Lite is exclusively available on XDA.  You can find the pro version on the Android Market.  Now, Mobile ODIN Pro has a few extra perks that the regular, old ODIN doesn't have.  For example, Chainfire includes EverRoot--an option that roots your ROM as you flash it.  With that, you can also automatically flash Superuser, and Mobile ODIN itself, so you're all ready to flash again when you reboot your new ROM.

Not every device is compatible.  But Chainfire made eight new devices compatible in the second update, and he says he's willing to work with Samsung phones.  If you install the app on an incompatible device, the app will let you create a dump file, which you can post in the app's thread.  If you can, also post a PIT file for your device.  Lastly, the developer says, he needs a kernel running ClockworkMod5, though it might work with CWM3 or 4.

To see if your device is compatible--or if there are plans for compatibility--and try it out, please carefully read the source thread.