One of the fastest growing trends today is combining data and functionality from several sources to create new services that provide a unique user experience. They’re called mash ups. Think Google Maps. Yahoo Pipes. Facebook Plug-Ins. Libraries are doing Web mash ups as well: Meebo Instant Messaging. Library Lookup. Bookburro. And, in a way, they’ve been doing all kinds of mash ups for years. Think story hour, open-shelf access, cafes, book lockers.