Yes, you read that right, YackTrack now has a premium API! The full announcement on the YackTrack blog has all of the details, but here is the key section:

You can review the API at the YackTrack Developer site. The API has only two methods at this point, searching for mentions of a keyword and searching for mentions or comments on a URL or blog post. I am planning on extending the API and social service coverage as soon as possible, without changing the current fee structure. There will continue to be a free version of the API which allows a limited number of API calls, but functions in the same manner as the premium plans.

For those of you that are more recent subscribers to this blog, YackTrack is a social media monitoring and comment tracking service that is a product of Regular Geek. So, if you are developing a social service that needs aggregated social data, take a look at the YackTrack API.