I was thinking they should make a DT video game. I was thinking it could be a point and click style adventure game based off the storyline of Scene's from a memory, where you would play as the dude investigating his past life trying to solve the mystery etc.
I also have another idea where you would play in the future where people have invented a device that records peoples dreams and you can watch them in theater. However things go wrong and you the player have to journey into peoples nightmares and dreams which are actually levels in the game based off dream theater songs. Some would be emotional and story based like heavy rain (Honor Thy Father, Root of All Evil, etc) some would be more fantastical like gears of war or warcraft (In the presence of enemies, Dark eternal night, under a glass moon) It would of course incorporated DT's music into the game, and maybe the band could write some new tunes.
I also think a dream theater inspired racing game would be cool...