Email Oracle, a nice service and extension for Google Mail (Gmail) to track your emails. It's a great way to see if your recipient opens your email. Unfortunately the service is shutting down. So I've found an alternative. More after the break.
Translating being rich of attention into real money is part of the game. An actor for example is not only paid for his achievements in the art of acting. His salary is strictly related to his popularity and therefore the attention he drives to a movie or theater. How does this affect bloggers?