Some tracks require you to have on full legged pants and closed toe shoes (incase you are in an accident). If you think your car will do 12sec passes, I have a helmet.
AAA card (just joking) but if you destroy your car they will tow you away
Ice, is good to have... you place it on your intercooler inbetween runs to cool off your engine... I sometimes leave just a few pieces of ice on the IC while I run to keep it a little cooler while your IC is getting heat soaked while waiting to run.