Don't know how many have heard about it yet, but here
is the Inter Quake Model Format. From what I see it would be quite a good idea to add it to Irrlicht Engine, most of all since it has a well maintained exporter for Blender that works, unlike many other animated model formats irrlicht uses. Also it is rather tiny, yet feature packed and seems to be quite the preferred format in the Quake and modding community.
EDIT: So far already achieved a 10x reduction in file size compared to DirectX format storing the same file data.
Going ahead already to see what I can come up with
H8L6L5M4G3H5M7N8S7N9O1R8J1P5M7N9O4P2Q5R6T7U4M3N8X6S5T8W (If you want the secret, why not 'TRY' decrypting it? )
This Door's lock doesn't need a key, the Lock is the key to open the Lock and you don't know how to turn the key...
Link: My Blog