The following has been added to the Zotero Group for Ancient World Open Bibliographies and the Ancient World Open Bibliographies Wiki.
Latin Language
Prose Composition: Bibliography
http://greekandlatin.osu.edu/programs/latin/latin_prose_comp/bibliography.cfm
Department of Classics, Ohio State University
No last update date; works vary in age (not a hotbed of publishing right now I suspect!)
This is a selected bibliography, including books and articles in English and German. There are a few sub-sections (Style, Of Dubious Value, and a few articles on whether prose composition should be taught.)
Ancient World Open Bibliographies 