fuel pump relay, coolant temp sensor (for the ECU), extra light bulbs, lots of fuses, wire (i always carry electrical wire)....hmm, theres much more i just cant think of right now. coolant or water, oil, p/s fluid, etc.
in the 6 years i have been driving E30 318's i have noticed that if you take care of them they take care of you, the only breakdown i ever had was my fuel pump died when i pulled my car into my dads shop to vacuum out my car, i knew the pump was going so it was no big deal.