Tray 1: Space Marine Bits. Pretty clear, I have a ton of space marine bits.
Tray 2: Planned Minis: This tray is where I group bits for minis in assembly. I stole this idea from Ron at FtW.
Tray 3: Catch All: This tray has a ton of random stuff from rubble, space marine vehicle bits, warhammer bits, chapter specific space marine stuff.
Tray 4: This tray was one recently cleared out of paint to make room for my Nid bits from my Assault Brood box. I have really not gotten this of the ground mainly because I have not been able to decide how to build them.
Ofcourse this is not all my bits. I have a few bags of bits seperated out for this project or that plus a bag of cities of death bits. I also have a small pile off uncut sprues still that I am working on.