Google have released a beta API for the adwords service.
The provide sample code in php, perl, .net and XML, so you can start "playing" around with it.
Full documentation describing the API, its functions and more can be found here
You can gain access to reports, keyword estimates and even create new content directly through the API. Imagine being able to run your adwords campaign directly from your desktop? You could even incorporate it into something like SugarCRM. Now that would be an interesting application.
I'm not a coder, so I'll have to wait for other people to do interesting things with it, but the possibilities are fascinating.
