Yahoo! gets most of its impressions in Y! Mail… and mail is notoriously hard to monetize.

Yet Google - who is printing money thanks to their search domination - invested heavily to get into email with Gmail. Is that smart management or allocation of capital? Not sure.

Of course, email is the biggest social networking platform out there (more here)… but then again, social networking inventory is really not monetizable… so what gives?

More on social networking’s woes with monetization here:

Related: Social Media

- Connecting the Dots: Why Social Media Fails at Generating Revenue
- Why Social Media and Advertising = Fail
- Dark Cloud, Meet Social Media. Social Media, Meet Dark Cloud
- Social Media Hype Train Continues
- When Will Social Media Get It?
- Why Social Media and Beacon Are Doomed to Fail and What Facebook Should Do
- Social Media Growing Pains