forgot my favorite scale
It's based on the diminished arpeggio
---------------------7-10-
-----------------6-9------
-------------4-7----------
---------3-6--------------
-----2-5------------------
-1-4----------------------

I also play it that way, makes a cool sounding sweeping pattern when you have to had tension to a solo

-------1-4------------4-7-4--------
-----3-----3--------6------6-------
-1-4---------4-1-4-7--------7-4----just keep on going up
-----------------------------------following the same
-----------------------------------pattern...
-----------------------------------
I picked up this one from Ron Thal, one of the coolest guitarist from the decade (that's also what Pettrucci says, he's got more credits than me...)