Bodleian Library: Broadside Ballads Project: Some images of ballads from the early 1700s.
Legends - Shake Loose the Border: Brief overview, with information on online and offline material.
Sixteenth Century Ballads: Transcriptions, music and bibliography.
The Oxford Book of Ballads: 176 selections by the anthologist Arthur Quiller-Couch. Indexed by title and first line.
The Traditional Ballad Index: Annotated bibliography of folk songs.