don't know about you folks but I really liked Kuroiwa's approach to koshi nage in this film clip http://www.youtube.com/watch?v=Vyxbvg4fJ-M
If you noticed his feet and body structure, it's a very casual approach, yet very nicely done. he seemed to move his leg, as he cross over, to make a hole for uke to fall in and to keep uke from falling on his leg. did i mention i really like his koshi nage? really really really like it.