The Last.fm Python library by Adrian Sampson is related to the API services that include access to music events, charts, and music players. This library in particular tracks metadata lookup, fingerprint lookup, and fingerprint extraction.
Shoudio is an amusing iOS application made to tag places with audio snippets. These can be anything a user imagines, and a lot of fun could be had with this. For example, integrating this into Geocaching could be a lot of fun, allowing things like audio hints to help Geocachers find the cache. However, the developers of Shoudio didn't want it limited to just one platform, so they released a Shoudio API to allow clients for other platforms, and fun mashups.
GoodGuide is a service that we have been using as a family for a while. It attempts to analyze a product holistically to produce a simple 1 to 10 rating of its 'goodness.' I am personally satisfied to see that the GoodGuide API will share this data with the world. Many consumers would love to choose products based on their total “goodness” but how can you possibly investigate all the companies and products that are out there?