Note: this post is from 2007, outbound links may be broken.
Max/MSP provides an easy way to turn your ideas into applications. Instead of programming everything from scratch, you can use a visual toolkit of objects, and connect them together with patch cords.
Likewise, Lily enables users to build programs graphically by connecting functional modules to fetch and direct the flow of data, play sound or video, add interactivity or display results.
There are already over 150 modules available for Lily, including web services modules for API’s like Flickr and Wikipedia, UI modules that wrap widgets from YUI and Google Maps, and more. Even database connectivity is possible.
Currently Lily is in private development, but a public beta should be out soon. You can already check some cool demos here.