GMDesk is an application that lets you run Gmail as a stand-alone application to do all your mail handling etc with. No need to open it up in a web browser, or have it clutter your workspace.
About Adobe AIR:
Adobe AIR runtime allows Adobe AIR applications to be deployed on computers and devices running the Linux operating system. In addition, Adobe Flex Builder for Linux can be used to build rich internet applications that deploy to the desktop and run across operating systems using proven web technologies.
· Adobe AIR