Categories and Players in Contextual Advertising

As the growing number of Web 2.0 rely on advertising as their main source of revenues, I read with interest a great summary published by SearchViews, on the four types of contextual advertising.

• Search-based Contextual: serves ads matching the content of a site/page as precisely as possible.
  Google AdSense and Yahoo Publisher Network are by far the two largest players, with AskJeeves having recently launched their own network.

• Channel-Based Contextual: serves ads largely based on the targets/demographics of the channel (site or portion of a site).
  Value Click is the largest player in the space.

• Behaviorally-Based Contextual: tracks users across a network of affiliated sites in order to build a profile, that is then used to target the user with relevant ads, as well as generate off-line sales leads.
  Tacoda and Blue Lithium are mentioned, and I would add Revenue Science.

• In-Line Advertising: these are the big, annoying, roll-over ads that pop-up if you get too close to them on certain site, or even are displayed on top of the text.
  Vibrant Media is one of the providers of these ads.

Worth a read.