I got to check out one of the new KRISS carbines there today, and I have to say, its a really trick little gun.
The bolt rides on a roller system that directs it back and down, kind of like a sideways L, which lets it be so compact.
And it takes glock 21 mags! pretty cool little thing, but I just cant justify the cost for something like that. Even still, theres absolutely nothing like it.