Originally Posted by AdultAds

Gangbangjoe,
Then there are adware companies that have contextual advertising capabilities. Their adware is bundled with popular products like smileys or screensavers and it is how those products are kept free to users. The adware sees the URL when a surfer surfs and can contextually target the ads. So if a surfer is on expedia.com you could pop your travel site. Some people have religion around whether that's cool or not, but it's legal. These networks include exactadvertising, claria, whenu, 180solutions, hotbar (there are more, but these are the top tier).