I started out by driving to homes and offices, but eventually I turned my teaching into a business, hired teachers, and rented an office. Now most of our clients come to our office. I still travel sometimes, but it depends on the contract. Yes, it can be a challenge to find a quiet place to work when you're in your student's office. (However, working with business people means that they take calls on their cell phones even when they're in my office.) Like you, if I have a laptop, an internet connection and some paper, I'm good. I do have the luxury of having a whiteboard on the wall, so that helps, too.
I mostly teach middle to high ranking businessmen. Occasionally that's in groups, but mostly it's 1 to 1 and always for 90 mins. I usually travel to them, but now and again I organise longer role plays where they come together at a neutral location. I work as a consultant in a school, but you could view that as a my good deed for society (It won't ever make me rich!).
The thing I miss about travelling to customers is that the equipment varies enormously. Some companies have well-equipped rooms and a "no disturbance" policy, others are shall we say, different.
Any sound files are carried on an iPod, occasionally I use a laptop and a couple of customers have SmartBoards, but mostly I rely on a lot of talking in the lessons backed up by "homework" on Moodle. Recently I've started experimenting with shorter lessons via Skype - I think that could become an important aspect in the future.