Interested in taking your mashup to the next level? Toby Somerville has a tutorial on Sitepoint.com which shows how to use the Zend PHP Framework with the Flickr, Yahoo! News, and Audioscrobbler APIs to create an interesting mashup. The Zend Framework has built-in classes to handle many Yahoo! APIs. Like some other PHP frameworks, it offers up an MVC (Model - View - Controller) design approach which typically results in an application that is easier to extend and modify while still maintaining a clean, modular code structure. If performance is critical to your mashup, consider coding in the MVC style without using a dedicated framework package. Our own Rasmus Lerdorf has his take on a no-framework PHP MVC Framework.