About those ads ...

LET’S say you wanted to build an advertising-supported online media business that took in $50 million a year in revenue. How many users would you have to attract to get there?

It sounds like MemeStreams may have the right approach:

It may be better for one or two people to create a relatively simple site — say, a hobbyist blog for guitar enthusiasts — and use a service like Google AdWords to, hopefully, make enough money to live on.

Here's the analysis.