What do you bring to the track with you for a day of racing?

I was curious as to what kind of equipment people bring to the track for a day or weekend of racing. Obviously you load up your race car and safety gear. What kind of spare parts do you bring? How many and what special tools? How elaborate of repair equipment? Generators, air compressors, welders, what ever? Obviously the answers will vary depending on the level of racing. Looking forward to your answers?