I was reading a news piece online when I was presented with a very cool ad/widget by Microsoft promoting its Sync technology.
The widget, seen here on the right, lets the viewer play a few cool games such as "Space Jumper", "Hyper Bunny", etc. The user can play the games in-line (in the context where the ad was presented without necessitating a new window). In addition to in-line play, the ad allows you to embed itself into your social networking page (Facebook, bebo, etc) by implementing a "Grab" feature.
The last feature on this gem of ad technology is the fact that a few of the games in the widget are "locked" until you use the "Grab" feature - thus encouraging the proliferation of the ad on social networks in a viral marketing-esque way. Nice!