They actually have some kind of system to come up with these songs. There's actually a guy who writes most of them - name escapes me - and there is a level of organisation (songsheets etc).
Sounds naff, but it obviously works.
EDIT Pete Boyle, I think
aye i remember reading something about that. It definately works, one of the few clubs where pretty much every player has a song, and the song is generally to a different tune n all.
Their away support is excellent (if full of arrogant, obnoxious cunts), but their home support is utterly, utterly dreadful, even taking into account that at almost every match in every PL ground, the away fans make much more noise than the home fans.
especially considering their home fans generally have more to sing/get excited about than most.