Application based upon Adobe AIR are becoming very popular these days, this is common. Featured apps can be browsed through the Adobe AIR home page itself while the Adobe AIR Marketplace is the place where developers can share and publish their creations, and where they can be downloaded.
The following four apps seems to be the most relevant for me, ranging from funny, useful or simply beautiful. In order to be advised on what is happening into the vast World of Adobe i have to suggest, Acrobat.com for My Desktop and the Adobe Developer Connection Developer Desktop, great tools to keep in touch and interact with the community. You can't miss Adobe Media Player, that shines for its clear interface and easiness of navigation through the content. On the productivity side i suggest to take a look at the fantastic kuler desktop to be wrapped by colors.
In brief kuler desktop is a color palette chooser, but defining it this way only doesn't describe neither its potential nor its features. It's possible to choose different predefined themes, or create your personal one and then share it to Mykuler section on the kuler web site and "synchronize" them with the application. Chosen colors can easily copied to the clipboard and are ready for the web.
Applications using Adobe AIR, for which is needed the runtime, nevertheless automatically installed if not present, are many and growing on number and quality, RefreshingApps.com "tries" to represent this behaviour and what is "used" to make AIR applications in its entirety, furnishing resources and feeding you with the most updated news.