AllMusic is a great website when it comes to content, but for some reason, they’ve never made it particularly easy for third-party tools to search the site. Like with the truly fantastic Alfred, for instance. Now, though, things have changed, & AllMusic has a senstible default URL scheme:

http://www.allmusic.com/search/all/{query}

This works for Alfred if you want to create a custom search for AllMusic. If you use a different search tool, just replace {query} with whatever your tool wants you to use.

(Thanks to the Alfred blog for this tip.)