10mm (battery clamps), 12mm (common size), and whatever the tension adjustment bolt is for the alternator belt.
straight pliers for spring clamps holding the coolant hoses. (actually, replace coolant hoses every 3 or 4 years)
multi-bit screw driver.
battery terminal brush.
glass cleaner and a old clean t-shirt for cleaning the inside of windows. (maybe a few sheets of newspaper to clean the outside)

There's not much you can really quickly repair on the roadside without parts.

take care,
ChrisS