There is a proven model with putting ads on the site, but it has to be in volume.
When you're in the mall, facing a human with a purchase in your hand, you're a lot less likely to drop those items and move on to another store.
Even the most intensive users of newspapers and magazines spend less time reading these publications than they do online or watching TV. TV and newspaper companies risk losing an entire generation of users unless they immediately start promoting their online products.
They are looking for certain red flags, verifying addresses, looking for certain behaviors that are tip-offs to fraudulent transactions,
The challenge is that the interface on a cell phone is so poor that anything you can do to reduce the number of keystrokes and the number of menus is a plus.