Star sign time! (No rising signs because I don't think their birth times are publicly disclosed)
John Petrucci - Cancer
John Myung - Aquarius
James LaBrie - Taurus
Jordan Rudess - Scorpio
Mike Mangini - Aries
Mike Portnoy - Taurus
Kevin Moore - Gemini
Derek Sherinian - Virgo
Charlie Dominici - Gemini
I think it's fun to speculate on this stuff, but of course it's far from hard science.
It "makes sense" that JP and JM would be members of two of the more introspective star signs (especially JM seeming somewhat aloof at times, matching the stereotype for Aquarius -- not to mention his creativity and unique vision).
The image of JLB and MP both "butting heads" being both Taurus is also kind of interesting. I always thought MP was an Aries (though he was born on the cusp between Aries and Taurus, so that is somewhat relevant).
Anyway, I don't know if anyone else digs this kind of thing here, but I figured I'd post it!