Just to get it out there and make it searchable, this is a list of all the things i take with me to the track:

2 qts of motor oil
2 bottles of motul rbf600
floor jack + 4 stands
electric impact
torque wrench
assorted tools for light work on car
clear vinyl tube for brake bleeding
race brake pads + rotors
at least 2 spare wheels
folding chair
sunblock
water
hat
Tire pressure gauge
camera
garden sprayer (on hot days w/ tires that get greasy)
air compressor

Things I take care of before track days:
Check Oil and MTF levels/condition and change if necessary
Check Brake Fluid/Replace
Check brake pads/replace
check tire pressure/set to baseline of 32 psi
wash it

FAQ's on:

Brake pads: OEM or OEM replacement pads can die an early death on the race track, and take you with them. I'd go with at least a very good street pad like the Cobalt Friction GT-sport, Carbotech xp8's, Porterfield R4s, or hawk HP+. Getting a dedicated set of track pads like CF Spec VR's, Carbo XP9's, or hawk blues is ideal.

Brake Fluid: In general you have 2 choices here--Motul RBF 600 or ATE Superblue. There are others, but these are the 2 most common. I like rbf600 the best.

Tires: run watcha got, but some tires--esp newer tires with lots of tread can chunk away at the track which may put a hurtin on your wallet. it's always good to have a dedicated set of wheels n tires to beat on at the track.