I use a Rook Endura Pro to store all of my small stuff: pens, pencils, enough dice for nearly any RPG (10d10, 30+d6, 3+ full polyhedral sets and more), highlighter, index cards, paper clips and counters (to flip).

I have plenty of dice to give to players who forget theirs, and the box saves me from having to scramble to get all this together at this last minute — I just grab it and go. This is easily my single favorite gaming tool.