2 tubes, patch kit, mini pump, partial tool kit (If I recall I've got all the tools for the bike except an 8 mm hex wrench, cone wrenches, cassete tool, and bb tool; those stay home), a couple of zip ties, a small bottle of lube, spare brake pads, and a pocket knife.

I put the pocket knife in after I discovered by accident that it was useful for removing a thorn embedded in my tire while changing a flat at home.

Maybe it's over kill but:

1. I've had two consecutive simmultaneous back and front flats once. That's four flats in the space of a half hour. Damn! I was a tad late getting to work on that day. Since then my only flats have occured within site of my home (stupid roofers!!)

2. I've had a brake pad get a piece of metal embedded in it. I changed it over my lunch brake, made for a much quiter ride home.

The next addition will be a bungee cord or two. I've come on some scrap lumber a couple of times and would have taken it home with me if I could have found a way to tie it down.