This has probably been mentioned before. Would it be possible to include on the 'Lexical and Grammatical Help" tool scriptural references to items not included on BW, but that are somewhat common in one's library. I'm thinking along the lines of the grammars BDF, MHT, Robertson, etc.
This is an interesting idea! I know of two cumulative indexes off of the top of my head, one to Greek grammars, and another to Hebrew grammars. What you are suggesting, I believe would be worthwhile. In fact, I think it would also be worth indexing other works, such as the Church Fathers, Rabbinic Literature, etc. I know of two indexes on the web to the OT Pseudepigrapha and possible NT allusions to it, or cross references between works, etc. These indexes would be helpful as well: http://www.bombaxo.com/otpindex.html (based on Charlesworth's OTP) and http://www.uni-leipzig.de/~nt/asp/par_ps.htm (German; based on citations given in the NA27).
Many folks may already own the print resources that you mentioned, and many probably don't want to pay for another copy--even if it's electronic, so I imagine that a cumulative index like what you are suggesting would be quite handy!
Let me suggest that you send a note to BibleWorks with your idea, that way they can file it and add it to the list (if they think this is a possibility).