Ad Brokering? Advice Please?

Hello All! This is a cross post, not too much response yet so here goes: Does anyone know anything about ad brokering? I had read about it in a report several years ago and supposedly its a good biz to be in. From what i understand, the broker works with 10-15 different newspapers and magazines and knows all of the prices,circulation, etc,etc about the papers.
Businesses call the broker, get the best deal and place there ads through the broker. The broker gets a commission from the sale and forwards the ad on to the paper. This can become a residual business. I had read that its typical that a paper won't sell all of its ad space so they have spots left.
I read that the broker niche is to sell these unused spots for a bargain rate. I don't know all of the ins and outs of this biz. I can't even remember where i read this report. Can anyone refer me to a site where i can read more?? Or does anyone do this?? I am just looking for some info. My wife is really looking for something she can do at home since we have small children. THis sounded like something that didn't require anything other than a phone and stationary.

Thanks for any sites, referrals or anything!!!
the big dog!