Okay, I like music when I run in the gym, but when I'm outside, I'm definitely a no headphones kind of guy. Indeed, I'm pretty much an anti-headphones kind of guy.
It's too dangerous out there, and I'm to spacey to deprive myself of one of my senses. . . I cannot tell you the number of times I've heard an oncoming car before I've seen it. On bike paths, the approach of a bike is often almost silent until it's too late. Running up Flatbush Aveue at 6:00 am in the dark, I cannot count the number of times I have reached out my arm to stop a running buddy from stepping off the curb, or been stopped. I also hate it when I'm on my bike, and I'm overtaking a runner on a bike path who is lost in his/her own private Idaho. When runners don't hear a biker, they are much more likely to jump unpredictably often in the direction of the cyclist. I really hate it when that happens.
Luckily, I am blessed with a bunch of running buddies who are excellent conversationalists. I also have a rich internal life, so I can manage to keep myself occupied, even on long runs. So, in my opinion, i-pods are for gym rats . . .