Google trends does not currently have a developer API – you can only get trends data by going to their page with your browser. A recent eWeek article mentions that they are planning to release one at an unspecified future date, which would be great, especially given the recent release of google charts.
Trends + charting = instant search analytics carved up any way you fancy. Personally I like the idea of a mashing up google’s image search, trends and charting to create incredibly useful web resources like the lolcat popularity graph.
Apologies to IE6 users (really, I feel for you guys) – PNG transparency is broken for you so the super amazing alpha channel backgrounds won’t display properly.