Who would have thought that even I could do it?! Here's my first C2 plugin Query String (alpha).
<img src="http://dl.dropbox.com/u/2306601/qstring.png" border="0">
It retrieves query strings added to your game's url through expressions, simple as that.
Now in Construct we can get these arguments by using the Query String object's expressions. QueryString.Get("user") will return "gamer" in this case.
How is this useful? You could think of it sort of as a command line method for C2 games. For example you could add ?debug=true to your game's url to start it up in a special debug mode.
I for one made this plugin because I wanted to pass whole levels in form of long strings directly to the game for an experimental project.
Also note that this doesn't work in preview mode, because apparently you can't add query strings to the preview localhost url. You will have to export the project in order to use this.
Download Query String plugin (alpha)
More features will eventually be added. Use at your own risk.