At Wikimania, James and I talked about the possibility of using WikiProject X to create recommendations. @Halfak said that his current capabilities for the tool: it would just be a matter of engineering it.
The tool would a)screen the references in top class articles for a WikiProject (likely FA, GA, B), b) identify the most frequently used sources in that topic through comparing either urls, or titles of certain reference fields- whether by journal (i.e. The Lancet), website (i.e. Newspapers.com), identifiers (doi, for example https://gist.github.com/hubgit/5974843) or publisher/via (i.e. JSTOR, Project Muse, etc), and c) recommend those resources to editors as places to start their research -> rather than what is happening now which is either manually curated lists, or relying heavily on editors previous knowledge of a field or research -> neither of which are reliable "guarantees" of quality research strategies.
The main risk here, is that the tool isn't used and that the recommendations tend to be very generic (such as Google Books).
Additional potential use cases: recommending research starting points in unreferenced tags, based on WikiProject or categories; recommending TWL and/or open access sources to newish editors.
*Capability to figure out article quality in WP articles: https://meta.wikimedia.org/wiki/ORES/wp10
*Cability to extract structured citation information: https://meta.wikimedia.org/wiki/Research:Scholarly_article_citations_in_Wikipedia