Flickroom (Windows, Mac, Linux): Unlike GeeMail, Flickroom does not mimic the user interface of its web app counterpart. Instead, Flickroom takes an opportunity to enhance and redefine the user interface for Flickr. Just like Flickr, you can view and search for photos, but Flickroom adds a nifty and well designed photo stream for enhanced viewing. With Flickroom you have all of the functionality of Flickr on the web with an enhanced and redesigned interface.
GeeMail (Windows, Mac, Linux): Needless to say there are a lot of GMail users out there. And while having your email in the cloud is great when you are not at your own computer, its always nice to have a native client that doesn't require sorting through multiple tabs just to find your email. GeeMail is a free application that gives Gmail a home one the desktop. With zero configuration and the same user interface as the web based version of Gmail, this desktop app is sure to be a hit for any avid email user. Also, with offline support, no need to remember to send that draft later. Hit send while offline and next time you have a connection, GeeMail will automatically send your email for you.
FoursquareX (Mac): While Foursquare may be designed primarily for mobile and the web, there are still quite a few reasons to consider a desktop app like Foursquare X. First, the integration with Growl allows for you to see when your friends check into a place right on your desktop. Also, with the integrated map feature, you can see where all of your friends are currently at. The desktop app also adds the convenience to check into wherever you are with a quick click in the menu bar. This desktop app is a must for any Foursquare addicts.
NoteSync (Windows, Mac Linux): Google Docs is great for storing documents in the cloud. But if you want to just take a quick note and save it to your Google Docs for later it s a pain. Typically you have to log in to open your browser, login to you Google Account, and go to Docs before uploading or typing what was supposed to be a quick note. With NoteSync you can now quickly open up your native app, type the note, and then it automatically syncs to your Google Docs for viewing and editing later.
Desktop apps that are extensions of your favorite web apps can be very useful and powerful. If you have a website that you would love to use as a desktop app then check out Fluid or Mozilla Prism for a quick and easy way to create native apps.