Working (offline) on Richer Plugin, I’ve expanded the list of reasons you’d want to use a Richer Plugin, i.e. Flash, Java Applets, Standalone clients, Firefox extensions etc.

Here’s the list of things Ajax can’t do on it’s own - what else is there?

• Browser morphing Adding buttons, toolbars, bookmarks, icons; changing browser behaviour.
• Local file access Reading and writing files on the user’s hard drive.
• Sound Playing music and sound effects.
• Rich graphics Providing rich graphics, changing dynamically. (This is gradually changing with the introduction of SVG in some browsers, but it’s no match for desktop graphics.)
• Keyboard shortcuts Providing a full range of keyboard shortcuts while avoiding conflicts with the browser’s own keyboard shortcuts.
• Hardware access Input from devices such as microphones, webcams, and gamepads; output to devices like printers and portable gadgets.
• Extended communication Communication from the client machine to locations beyond just the base server, and in protcols other than plain old HTTP.
• Operating system interaction Catching events such as shutdown initiation; changing preferences; popping up alerts; reading hardware information.