"Dapper is a free, web-based service that enables users to easily create an interactive feed from any website for consumption on any platform: RSS reader, iGoogle, enterprise mashup, mobile phone, etc. Users can make a dynamic feed (API) that changes based on user input for any website. With Dapper, anyone can create RSS feeds, universally embeddable widgets, and XML (among other formats) for any website." [from Answers.com]See this short demo video that illustrates how easy it is to make a "Dapp".
Dapper Facebook AppMaker:
"Turn any website into a Facebook application -- no programming required!" "Use your own header, footer, background styling — really make it yours — and with absolutely no programming. If you can make a Dapp, you can make a Facebook app."