anthem has to be stirring (like 'You'll Never Walk Alone') - not too fast and not too poppy/lightweight. use your imaginations, and if need be come up with something a bit obscure. main thing is that it has the capability to be a good sing-a-long (unlike, say 'right here, right now' - which is exactly the opposite of what we are ooking for)
here's an off the wall one to get the ball rolling -
rod stewart's 'hangbags and gladrags' (used as the theme tune to the office) - kind of apt given arsenal's financial state!

more suggestions welcome, and i'll chip in with a few more myself when they occur to me.