Some sea-songs:-

Rolling down to old Maui
Donkey riding
Blow the man down
Shenandoah
Haul away Joe

Others (if not on Mudcat, should be on CDs by the people listed):-

Slip-sliding away (Paul Simon)
Bottle of wine (Tom Paxton)
Leaving Nancy (Eric Bogle)
Banks of the Ohio
Johnny I hardly knew you

Graham.