If you have high bandwidth access, I just uploaded a video on multi-finger tapping.
Over the next few weeks I'll be adding videos to all my tapping stuff so eventually there'll be about 50 lessons for all the stuff below.

http://www.guitartricks.com/lesson.php?input=1580

http://www.guitartricks.com/2000/trick.php?trick_id=1873&s_id=13
http://www.guitartricks.com/2000/trick.php?trick_id=1961&s_id=15
http://www.guitartricks.com/2000/trick.php?trick_id=2059&s_id=16
http://www.guitartricks.com/2000/trick.php?trick_id=2484&s_id=21