Reproductions of Sam Pepys' large broadside ballad collection (the originals are held at Magdalene College, Cambridge) can now be seen online at the University of California-Santa Barbara:

http://emc.english.ucsb.edu/ballad_project/index.asp

Unfortunately there is no index, which makes looking for things a bit messy; though there are various search functions. Anybody who has a copy of Helen Weinstein's index (out of print but available as a remainder from numerous dealers, at prices from the sensible to the frankly bizarre) should have no trouble finding things.