Gil,
I've been depressed at times, too, about no one wanting to hire me, so I know what it feels like not to have a job - or one that is almost not a job. Maybe the boss at the cab company doesn't think people will like you or something. Why not try and build-up your own client base. Make up business-sized "cards" on one 8 1/2 by 11 sheet of paper. Go to a local copy machine (5 cents per sheet) and make some copies. Then begin to pass these out to people you meet at random - in a hotel lobby, bar, etc. Have your name on it and the cab company's phone number. Tell the people to "request" you as their cab driver. Even if you don't get to pick these people up, you will be creating a demand for your services in the bosses mind. He then will offer you more days of driving, thinking that "this guy is really popular with my customers".
Remember to put a smile on your face, even if it hurts to do so. Learn to hide your pain when out in public.
NewLight2