Everyone here has their own list of what they take with them on their commutes, but what kind of bike equipment do people keep at home? Is there certain equipment you keep an extra set of so you don't have to run to the bike shop every time you need it?

I was looking at my commuting outfit today and realized that I have no extra tubes, tires, or anything else one might want to keep at home. I work some really weird hours so running to bike shop is not always an option should something come up.