There's a few time honoured songs such as "Danny Boy" that are usually good for fetching a tear or two, and my mother loves to hear me play and sing "Hard Times Come Again no More". Personally I'm sick of doing these songs but none the less, they are emotional.

Recently I had the pleasure of hearing Martin Simpson's version of "Hard Love". This one really moved me. Check it out if you see it going cheap anywhere, and keep that tissue box handy!