Google have at the publishers disposition a wide variety of ads. In its main site you will find all the formats of AdSense. There are six types of different publicity in AdSense:
Text announcements - The most important, those than will gave you more gains and the only ones that are configurable.
Graphical announcements - Images instead of text Show. They can be useful to obtain income by CPM, with no need of clicks.
Video announcements - Similar to previous but with animated or video format in contrast with static graphic ads.
Blocks of Links - Very useful for the user and if well optimized, they can be very profitable to a webmaster. They are based on connections to searches predetermined by AdSense on certain words, reason why each click in a publicity connection has a very high CPC.
References to products - products of the own Google Sell. Publicity of payment by action can be considered, and in some occasions they are a good complement to the gains of AdSense. Nevertheless, most of the occasions they are not very profitable.
Thematic announcements - They are announcements of text but designed and focused to certain events and local celebrations. They are not very habitual.