1. take pictures of yourself with your camera phone (as soon as I figure out how to get them off my phone, I'll post them). I look like an alien in a couple of them and one has the sun shining from behind right where my eye should be. Totally cool.
2. Talk to a dog. I had my dog Paddington along for the ride. He pretty much went into car coma in the back seat but I could talk to him and he would look at me. That was fun.
3. Cry. Driving for a really long way by yourself gives you lots of time to think, analyze, get psychotic about things you really shouldn't. It's also a perfect time to just cry and yell and scream and get all of those emotions out. I recommend doing this during the dark night portions of your trip so that other drivers aren't scared by your emoting.
4. practice driving with your knee. I find this very practical when you are speeding down the highway at around 80mph and have a real need to eat a sandwich and use both your hands. Props to my dad for teaching me this excellent driving technique.
Any other great tips are welcome!