It's not something that I think much about, but most of the errands I run are within a 2 mile radius of my house. The bank, the grocery store, the library... all are within walking/biking distance. Today I did what I should do every day and traded my car keys for a pair of running shoes.
Amazingly enough, running errands by foot when everything is nearby doesn't really take much more time than driving, considering I can bypass the surface streets and cut through walking trails, not have to worry about parking or navigating the lot with other crazy drivers. And actually, it saves time because I don't have to fit another hour workout into my day - it's covered!