As far as I can tell, this song can be played in either C (Am-F-C-G) or in G (Em-C-
G-D). I may be a little bit off on exactly where the chord changes go, but it 
should be close enough. you can listen to the song at http://www.youtube.com/watch?v=lNa6R8dFvLs:

Verse 1:
Am(Em)                   F(C)
Who was and is and is to come
C(G)                       G(D)
The Savior, Redeemer the Father the Son
    Am(Em)                    F(C)
His Spirit is on me a fire within
  C(G)                   G(D)  
Creator, Sustainer, Beginning and End

Chorus:
            Am(Em)             F(C)
The Great I Am,    the Great I Am
            C(G)               G(D)
The Great I Am,    the Great I Am
            Am(Em)             F(C)
The Great I Am,    the Great I Am
            C(G)               G(D)
The Great I Am,    the Great I Am

Verse 2:
You are everything I will ever need
To complete every thing You are asking of me
I lay it all down for the sake of Your Name
Here I am God, use me, set me aflame

[Chorus]


Bridge:
Am(Em)
You are dancing and singing the Father's song
F(C)
You are dancing and singing the Father's song
C(G)
You are dancing and singing the Father's song
G(D)
You're rejoicing over me

          Am(Em)
You are a good, good Daddy
          F(C)
You are a good, good Daddy
          C(G)
You are a good, good Daddy
          G(D)
You're rejoicing over me