I've written a script for commenting out multiple lines of code at a time - it detects what language you are using from the file extension, and then adds a comment symbol at the start of each selected line. If the selected lines are already commented out then they are uncommented, so it lets you toggle comments on/off as needed. Languages supported include Java, JavaScript, PHP, C-Sharp, Perl, Ruby, UNIX Shell, and VB - it can also comment out sections of an XML/HTML document.
Its a bit long to post here, but you can download it from http://codebox.no-ip.net/controller?page=misc.UeBlockComment


