Havent seen John Petrucci mentioned in this thread, he does everything from prog rock to shred to classical and everything else in between. I just heard an amazing cd with him and the keyboard player from Dream Theatre where they basically jammed for a few hours on front of a crowd. It sounds incredible, check it out if you like JP.
Satriani is also hugely versatile, his techno album is testament to that. Another great player worth a mention is Greg Howe, neo-classical, shred, prog, fusion, accoustic, rock etc.