Many people hate advertisements. The thing is advertising reduces and sometimes removes the cost for a consumer to consume some form of media. You do not have to pay to listen to FM or AM radio because there are ads. Satellite radio you have to pay for since much of it is commercial free.
Online content and services need to make money in order to operate. Just having a website up and running costs money. I encountered the following and thought it was brilliant. A very capitalistic solution to security.
This dialog is a form of a captcha: an interactive applet that requires human interaction to prove a "bot" is not using a site en masse. Hence, captchas are a security mechanism to ensure only people are using a site and spam bots are not taking over.
By incorporating the ad into the captcha and typing in part of the ad, you get product retention. I imagine this form of advertisement must cost a little bit more, but what a brilliant idea. Advertisement retention and security all in one!