What Extras Should I Buy When Buying a Laptop?

HarleyPig asks: "I'm using my tax return to buy a laptop. I don't want to know which laptop to get (that's a religious discussion I'd like to avoid). What peripherals do you find yourself wishing you'd bought, or have ended up buying? I know I'll need a mouse, extra cabling, extra batteries and some kind of case to hold and carry around the laptop. What else should I consider putting in my list of stuff to buy with a laptop?"