[tucsonjwt]

X2 - but most important get road service if you don't have it. The best deals on road service can be had from non-insurance company offers - like credit card offers and the like. Make sure the coverage includes some significant distance, not just 10 mile tow limit. Even AAA road service can be worth it if you have one breakdown.
Just bring water to drink and you can also use it in your radiator if you have a leak. Keep your extra belts and hoses/clamps when you change them out so you can use them in an emergency - same for plugs and plug wires if you change them. A few extra quarts of oil is a good idea, especially if you have an oil leak like most of us do - sustained high speeds cause more oil to leak out. A set of sockets and screwdrivers is handy to have all the time. I would check the bolts on your crank pulley - I had mine loosen up and had the pulley fly off on a long trip - lots of potential damage there. A set of long jumper cables and maybe a jump start battery pack wouldn't hurt. I keep a bottle jack and wood blocks for chocks/jack assist even though I have all the stock jack parts since I think the bottle jack is safer to use.
An extra cell phone with charged battery is not a bad idea, in case you lose your regular phone or it goes dead or is out of range. I have a pay as you go cheap phone which you can get for $20-$50 which I actually use as a primary phone, since I don't make many phone calls - I use the net for most communication. You can use that second phone periodically to use up the minutes before they expire, or just add $10 to it when you need it.
Some high energy snack food that won't melt or go bad will be good.
Bring $200-$300 extra cash - not every place takes credit cards and if you break down cash might help encourage someone to help you.