Honestly - a spare laptop battery? And who uses mouse pads these days? Or a mouse - all laptops have built-in pads or buttons and you should be driving your presentation wirelessly anyway. Spare projector bulbs are ruinously expensive and notoriously fragile. Headphones when presenting - surely not? And if you need notes, you don't know your presentation well enough.

if you're travelling further than a few hundred yards to deliver this presentation, you're going to need an assistant to carry all this and woe betide you if you try to get it all on a plane!

My minimal list would be:

- laptop
- backup copy of presentation on USB drive
- wireless presentation controller + spare batteries
- business cards (amazing how often I forget these)
- mobile phone with site contact details stored
- power adapter if you're presenting abroad

Surely that's enough for the most careful and prudent road warrior!