A lot of you seem to carry a lot of stuff with you, which is great!

However, I seem to carry very little with me. The only bike related things I carry with me is a portable pump and a patch kit. I've obviously got a light, helmet, and I have a fender which I haven't got around to installing yet, and I'll probably end up waiting until it rains next. I just don't think bringing a crapload of things is necessary, it adds too much weight and the chances of getting a flat are too rare for me. But again, it totally depends on where you're biking.

I've got an 8mile (12.5km) commute one way and if I happen to get a flat, I bike really close to a bus route and take the bus, usually ending up at school around the same time. It's a pain in the ass to have to wait til I get home to fix it but like I said, I don't get a flat often enough to take a lot of things with me.

Base what you need to bring on your length of commute and the location!