My gaming crew and i are already wondering what it'd be like to play some of the other unmentioned Chapters!
Salamanders
Alpha Legion
Nightlords
White Scars, especially these guys in my opinion, with all the crazy hunts they go on.
Lets come up with some good rules for these and other chapters you have in mind to waste some time until we get the book! I'll get the ball rolling for us. The Salamanders could get a crazy bonus to being resistant to fire damage. A drop in their fellowship score because of the red eyes would probably work as well. Giving them a crafting bonus to weapons and armor would reflect their talent at creating them. I also think some kind of bonus to toughness would be mandatory.