You might be able to use Albert by using a mailto tag embedded in a flash button to activate a script on a remote machine. Another option would be to use AppleScript over IP. I haven’t tried either method, but it does seem possible. I’d be careful of security issues in either case though.
The URL Protocol Messaging isn’t your solution… it lets you define new protocol types (e.g. http:// ftp://) that get passed to your script, but the user’s browser has to know how to handle your protocol.
However, all is not lost, what you describe can be very easily handled via AppleScript CGIs.
Yes, that’s entirely possible - with a couple of caveats.
First, if no user is logged in, it’s unlikely that the script will be able to launch any graphical-based apps, so you’ll need to add error checking to your script to make sure you can launch apps, which isn’t a big deal but needs to be said.
Secondly, Mac OS X Server comes pre-built with AppleScript cgi support built in, but the client version doesn’t. To run AppleScript cgi’s on Mac OS X client you’ll need to get a copy of ACGI Dispatcher ($15) from http://www.sentman.com/acgi/index.php
This enables apache to propertly handle AppleScript cgi scripts.