How can I make the middle button open my Applications folder? (Mighty Mouse)

Open script editor and paste this into it

Code:

try
	tell application "Finder"
		set tpath to path to applications folder
		open folder tpath as alias
	end tell
end try

Save it as a script and then place it in /Library/Scripts. This will allow you to select it as an option in the mouse preferences and hopefully it will work. I can't test it out unfortunately.