I guess nobody has mentioned him yet.
He plays guitar and keyboards in Vai's band now but he had some pretty good neo-classical albums in the late 80's as well as some amazing fusion stuff with Planet X (with Derek Sherinian) and CAB.
I would deffinately recommend a listen to CAB or Planet X for something a little different.
After listening to his CD's and seeing him live, I honestly believe he is a better al;l around guitarist than his boss Mr. Vai. His playing is way more consistent and proficient, and he also has the melodic variety and innovation which most shredders do not have. The instrument just comes more naturally to him than to other guitar players. This dude is a freak. He is an AMAZING guitarist. There is nothing he cannot play - really. He is also a concert pianist and violonist. [:I]