Not owning a laptop, I’ve found my little USB thumb drive to be very useful when I’m running games at someone else’s place.

It lets me carry support material, like the SRD for D&D, backup game notes and character sheets, and also download stuff that was generated during the session — for me, that’s always been session photos; for you, it might be something else.

It’s not a perfect solution, but it’s so small that there’s also no real downside — and it’s a great place to back up your campaign data, even if you don’t access it during the game.