Chris - if this was the David Murray Collection of Broadside ballads on the topcities website then you stumbled on a site that is being developed as a teaching aid for Social History at Glasgow Uni and for a Broadside Ballads class at the GU Crichton campus.
The topcities site is a just temporary site, a frames site (which I feel will make the ballads harder to view) will appear shortly on the Crichton campus server. Very much as you suggested, these broadsheets were published, as you see them, with no music, they would either have been well known in their day, or a singer would sing them to a popular tune of the day. The new site will have some recordings on it, initially about ten broadsides will be covered but the aim is to have recorings for each of the sheets (over 250) eventually. This is all down to availability of further funding.
If this funding is forthcoming it is hoped that some of the 2,000 (approx) unclassified & unsorted broadsheet ballads that Glasgow Uni posess in their special collections vaults can be included in the project.
All the best,