Good question. From the recently launched free ad management/serving platform for small-to-medium advertisers, to search analytics, site search, tracking for their Audio and TV ads, not to mention the original gMail, GOOG-411 voice search, Google Docs (trying to give Microsoft a run for its money) ... the list goes on.
The giant continues to secure multiple touchpoints with Web users--the better to serve them ads with. The question is, can other marketers learn from that model or do something similar (without being EVIL)?