Arguably the cheeriest song about prolicide this side of Violent Femmes' "Country Death Song." From The Decemberists' 2009 record The Hazards of Love, which is probably being reenacted at a renaissance fair near you.
Portland band The Decemberists released their newest album What a Terrible World, What a Beautiful World last January. Their new EP Florasongs is out now. More information on the bands website here:http://www.decemberists.com/