Garett Rogers spends some time reading the Google Related Links Terms of Service page and discovers some interesting points:

You understand that all information, data, text, software, music, sound, photographs, graphics, video, advertising, messages or other materials made available through the Service or linked to from the Service ("Content") are the sole responsibility of the person from which such Content originated.

As the TOS suggests, future versions could have tabs for music, photos and even video. Google may even chose to display ads in the link box.

Google already has a comparison shopping database called Froggle. With Google Related Links, Google might be planning to build an interactive advertising unit like Chitika eMiniMalls ?