Laptop Backpack:
Laptop - which I use to run DnD4e Combat Manager (it tracks all hit points, conditions, powers, etc.) I keep character wish lists, upcoming encounters, various notes, and a few other things on for gaming.
Folder with notes and DM screen if I need it.
Dungeon Tiles Set
Pens/Pencils
Dice Bag
Tackle Box Containing:
Assorted Tokens
Assorted Minis
Extra Tiles (some from the new Red Box)
Plastic Storage Container holding my home-made magnetic condition markers.
Plastic Bag containing flat on the bottom, circular top glass beads (I use these to represent action points).
Going to be getting my own battle mat, but for now one of the other guys is providing one along with wet-erase markers.