http://www.guitartricks.com/tutorial.php?input=409
I also have a tutorial on right hand strumming exercises. This one is pretty much an opposite of the the downstrokes. In the downstrokes tutorial, I use a more metal aggressive speed motion, this one is on how to gain speed by relaxing your hand and concentrating on the motion.
http://www.guitartricks.com/tutorial.php?input=275
There's also my beginner's tutorial on picking. Altho this seems trivial, it forces you to work on being constant in your execution whether you're using downstrokes, upstrokes or alternate picking. The picking principal can be used on with any scales. I created this tutorial because I saw a lot of guitar player lacking good upstrokes and in the end, it had a negative effect on their alternate picking.
http://www.guitartricks.com/tutorial.php?input=372
Finally you could look at my dexterity tutorial. It has some exercises that uses string skipping which is also something you want to work on if your right hand can't keep up. It important that it can skip easily over string to follow your left hand. It also has quite a few sweep picking so you'll be tackleling a lot of techniques.
http://www.guitartricks.com/tutorial.php?input=401
So with these 4 tutorials, you're going to work on picking movement, wrist dexterity, being constant when switching to different picking techniques and string skipping. You see, you won't really work on speed, but rather on motion and execution.
For speed drills, check out Christophers speedy ideas :)
http://www.guitartricks.com/tutorial.php?input=213
http://www.guitartricks.com/tutorial.php?input=287