Well you may need a lock and chain for your bike while you visit the shops.
I'd say (like many above) gloves. They've saved my hands on two occasions when I least expected it.

.....as a matter of interest, I do most of my ridng in the city and I carry very little. No tube, no pump, no tools etc...
Because my bicycle use is mainly for work to visit clients, I don't have time for repairs on the run, hence just the cable lock.