Side note: my favorite radio show is uploaded to Grooveshark and the other day I needed to listen it offline, so I just used a proxy (fiddler) and save the stream from the proxy session console. There is an API where you can do the same, I think, because is just one request with the location of the MP3 audio. There are a lot of apps for downloading mp3 from Grooveshark but they usually came with a lot of crapware.