When you guys are commuting to work/school/etc, what tools do you bring with you? I want to set up a section of my commuting pack dedicated to tools and general maintenance carry. However, I'm not sure about what I should bring. I'm having trouble finding a balance between a light load to over-doing it.

For sure I will bring tools for changing a flat. I have a singlespeed, so I'll bring a 15mm, tire levers, small pump, patch kit.

But what else do you guys carry with you, whether on person or in bag?

Thanks