Oh my! Didn't know this -

Kenji Kawai held a Live Concert in 2007, called Cinema Symphony. Hint from one of the youtube comments: "maximum volume = maximum experience." (The default volume of those videos is a bit low.)

Ghost in the Shell: Innocence - Kugutsu Uta 3 (Kagirohi Wa Yomi Ni Mata Muto)
This song does not only have a long name. 10 minutes of pure epicness!

Ghost in the Shell - Reincarnation.
Short introductory speech by the master himself in Japanese (I don't understand that much, sadly), the song starts at ~1:38. This one is shorter than the one before, but also stunningly beautiful.