Mary, the Slug of Tralee
All The Old Slugs Are Past And Gone
The Londonderry Slug (Danny Slug)
Creeping Slug
God Save the Slug
Poor Slug Tray
The Very First Time I Saw Your Slug
and of course Wagner's Slug Cycle.

And tunes too: the Slug on the Mountain, the Slug that Shakes the Barley, the Slug at the Spinning Wheel, Slugs of Ballysodare, Jenny Picking Slugs....