The Bandsintown .NET SDK by Damian Karzon interacts with the API to access music events features, including artists and venues. Author's .NEt client available at http://dkdevelopment.net/2010/04/29/smack-my-bitsharp/
The most popular API, in terms of mashup count, is far and away the Google Maps API, which accounts for 41% of all mashups. But when it comes to the most popular pair of APIs, Flickr and YouTube mashups are the most common. Not to be outdone, Google Maps joins Flickr in a near second place.