OK, so far I have the following:

- floor jack
- torque wrench and associated sockets
- torx/flathead/phillips drivers
- tire gauge
- spare belt
- spare plugs
- can of fix-a-flat
- Invisible Glass cleaner & towels


Anything else?

 

Jack stands, coolant, oil, brake fluid. Brake bleader if you have one, put on your wish list if you don't. If you change out your pads for track days, be sure to take your old pads with you for spares.

 

Plus assorted hand tools to service brakes. Instead of Slime, get a good HD tire plugging kit and some inserts. Much easier and faster than Slime.

 

Orange hand cleaner (pumice based) and paper towels.
A tarp for when it rains and your floor mats are about to get soaked.
A 2x4 to use with the jack
A breaker bar or your torque wrench won't last long

 

Claymore,

You need to coordinate with a good Mini track buddy with all the tools. That is how Veggi and I do it. He seems to always have stuff that I need and vice versa.

 

Chair

Pulley tensioner tool (buy one - it's worth it if you need it)

Extra track pads - possible if you drive aggresive enough that you'll need them if you start out with worn track pads

Extra oil for topping off

Funnel if your running a strut tower brace

Chalk to mark your tires (see if they are rolling over)

5 gallon fuel tank (or two!) if you don't feel like paying inflated track prices

Light weight jack and stands

Tool box

Brake fluid and bottle

Air pressure gauge

Work gloves

Wax the leading edges of the car to make clean up a bit easier