I did the search for you, seems fitting as I was the last one to ask this question.
http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,316001/highlight,spares+box/
In the end, I carry
Tools:
Wrenches (Racheting)
11mm
13mm
15mm
Screwdriver (All in one)
Socket Set
SAE & Metric
(You never know who used what)
Parts
Fuel Filters
Fuel Line (Couple sizes & Lengths)
Oil Filter (Use the good stuff)
Spark Plugs
Assorted Fasteners
Fuses (Enough to replace every single fuze twice)
Lug Nuts (enough for a wheel)
Points
Condensor
Fluids
Oil, 2 quarts (You can toss them up front under the windshield wipers, or in later cars behind the supports in the trunk
Coolant 50/50 mix
Gasket Maker