I noticed this new published research on relevance ranking, published in SIGIR '13: "A novel TF-IDF weighting scheme for effective ranking". It is supposedly better than the other popular ranking algorithms like TF-IDF, BM-25, etc. http://dl.acm.org/citation.cfm?id=2484070 The author calls it "MATF" for Multi Aspect TF. He is presenting it now at University of Maryland but I'm not in the area to attend. It'd be cool to see a Lucene Similarity for this.
~ David
