The song is done in bar chords and Glen Hansard wrote it after his niece told him 
that his music was depressing.
I couldn't find the chords so i looked at all of the different video's on youtube 
and i then got the chords by looking at the fret board and listening.Enjoy

Am:                Dm:               Em:
E[---5---]         E[---5---]        E[---7---]
B[---5---]         B[---6---]        B[---8---]
G[---5---]         G[---7---]        G[---9---]
D[---7---]         D[---7---]        D[---9---]
A[---7---]         A[---5---]        A[---7---]
E[---5---]         E[---5---]        E[---7---]

intro: Am  Dm  Em

VERSE 1:
AmI'm (x02210@1)the banana man, I go uppa that tree,

Dm (xx0231@1)                  EmI (022000@1)go downa that tree, I go home for me tea

AmI'm (x02210@1)the banana man, And I drink me Coca cola,

Dm (xx0231@1)                           EmAnd (022000@1)I play me rock'n'rolla down by the sea

CHORUS:
Am (x02210@1)            Dm (xx0231@1)    Em (022000@1)Everybody likes bananaaaaa's oooohh

VERSE 2:
AmI'm (x02210@1)the banana man, I go uppa that tree,

Dm (xx0231@1)                  EmI (022000@1)go downa that tree, I go home for me tea

AmI'm (x02210@1)the banana man, And I drink me Coca cola,

Dm (xx0231@1)                           EmAnd (022000@1)I play me rock'n'rolla down by the sea

CHORUS:
Am (x02210@1)            Dm (xx0231@1)    Em (022000@1)Everybody likes bananaaaaa's oooohh

Banana ah   banana ah bannnnna

Back to intro :Am   Dm  Em (x2)
OUTRO:
Am (x02210@1)            Dm (xx0231@1)    Em (022000@1)Everybody likes bananaaaaa's

Am (x02210@1)            Dm (xx0231@1)    Em (022000@1)Am (x02210@1)            Dm (xx0231@1)    Em (022000@1)Everybody likes bananaaaaa's

Enjoy :)