as chosen by an "extensive" youtube search and in no particular order and not limited to alliances that currently exist:P
I also don't claim that all these songs are good but this should not be interpreted as an indication of my views on these tags past, present or future:P

RD: http://www.youtube.com/watch?v=anGYFI_hmII
SOL: http://www.youtube.com/watch?v=kk_6kwZbNJs
PDM: http://www.youtube.com/watch?v=pofqHfSvy_8
Monsters: http://www.youtube.com/watch?v=Ye8mB6VsUHw
TIE: http://www.youtube.com/watch?v=KReoTOZK9W8
LaF: http://www.youtube.com/watch?v=WpU0ndYPMzU
LCN: http://www.youtube.com/watch?v=OZQ8CKsZDIs
imag: http://www.youtube.com/watch?v=z_rIskAu9ow
Rival: http://www.youtube.com/watch?v=dzmBVqNzkuQ
omega: http://www.youtube.com/watch?v=tOKKQA0b2zo
evo: http://www.youtube.com/watch?v=VJrVNqFK4og
MD: http://www.youtube.com/watch?v=aXoff2ObF_c
ICN: http://www.youtube.com/watch?v=1y5Nd3qImJM
The Death Knights: http://www.youtube.com/watch?v=UPhJNo-17cg
WB: http://www.youtube.com/watch?v=ctaCXCvd4ao
MGP: http://www.youtube.com/watch?v=pD5rND-Nlq0
THE MIGHTY CLAN [DANGER]!: http://www.youtube.com/watch?v=HD5tnb2RBYg
and finally
SoF: http://www.youtube.com/watch?v=dnPqWLEKmuM
ok maybe not how about
SoF: http://www.youtube.com/watch?v=BkTjuA6yKVI