Here is a short list...and just what I happen to do. Others might disagree:
Engine Oil every 3 or 4 events (weekends)...unless it looks dirty sooner
Diff oil every 4 or 5 events (for Torsen), or every single event (for MazdaComp)
Transmission oil every 4 or 5 events...although I probably don't stick to this as I should...
Clean air filter and re-oil every event or two.
Nut & Bolt (every nut and bolt you can get to) the car after each day if possible, but certainly every two. Be sure not to forget the lower ball joint bolts, including the one that goes straight down (next to the shock) as it is easy to miss...and mine occasionally loosen up on me. This task mainly applies to suspension, brakes and engine compartment...but you'll figure out what works for you.
I choose to remove the brake calipers to re-lube and inspect the brakes between every event. Some folks say I'm nuts...and I may be but it works for me. While in there check the torque of your rear, upper slider (that the caliper slides on), as some tracks can make them back out. I bleed the brakes between every event.
Monitor each wheel hub often, for sure between events. I re-pack front wheel hubs twice a season (every 6 events or so) or after any rain event. There probably have their own (different) schedule for this.
I have suffered a stuck thermostat and got my motor very hot...so I change thermostats every few events if I stick to my plan. There are plenty of other options here including drilling out the thermostat. I haven't gone this route. Also, use distilled water and water wetter.
I change the fuel filter once a season (usually over the winter). This is probably over-kill.
That's all I can think of for now...