Sorry, Simon!
I have to throw in my two cents before you put the kibosh on this thread. Let's see if anyone recalls these awesome intros:
1) "Equinox" by Elegy (from the album "State Of Mind")--The build up from the keyboards into the choir with the same melody is just haunting, and then Henk Van De Laars (one of the most underrated guitarists in prog metal) comes in with the perfect lead to go over all of it. The icing on the cake is that it goes into "Visual Vortex!"
2) "3rd Challenge" by Angel Dust (from the album "To Dust You Will Decay")--There's something about power metal intro tracks from the 80s that really tickles my fancy. Kamelot-styled intros sound great, but you can tell that it was all done on computers. With this Angel Dust intro, I think you can truly imagine all of the musicians required to pull this off being on stage before the band comes in to kick your ass with "Mr. Inferno."
3. "Horizons" by Ion Vein (from the album "Beyond Tomorrow")--Remember when Ion Vein was a prog metal band? Boy, do I miss that. There's a really subtle piano part playing along the chugging guitars that are also kind of subtle amongst the overlying keyboard theme. It's also an intro that actually has drums! Just as it is with "The Hellion," it's nice to hear an intro that can actually be played by the band who released the album!
Forget the honorable mentions! If they were that honorable, they would have made the list!
Stay metal. Never rust.
Albert