Many college/university residence buildings have T1 lines. So it could be people in the dorms there.
Also, some new apartment buildings boast high-speed internet access, wired or wireless, included with your rent. They would likely be using one for that.
Hotels might.
And there are still some businesses that just don't bother with much IT security.
A residential user can get one as well - it is seldom done because of the cost, but I had a friend who was a gamer, her husband was also a gamer, they used their computer for all TV shows and music downloads, and they have several college kids boarding with them who were also gamers. The local broadband service providers couldn't keep up, and they keep getting disconnected under the "appropriate use" policies (bandwidth caps). So, they got a T1 line for the house. I don't think there would be that many people who would go that far, but there must be some out there.