Lexicons, Indexes, Intertextuality and "Hacking" BibleWorks
Muraoka's Greek English Lexicon to the Septuagint would be a great add on. Some electronic version of his A Greek-Hebrew/Aramaic Two-way Index to the Septuagint would be a great addition to the Tov-Polak parallel MT/LXX, given that the index includes different recensions as well as apocryphal lit. I think that an index like this would not be redundant if it could be used to expand the search features of BibleWorks. (Imagine a cross-linguistic search feature where one could click a Greek word and then be lead to a search of all Hebrew and Aramaic reflexes in the OT and Qumran.)
I also think that Danker's Concise Greek-English Lexicon of the New Testament would be a worthy addition (as mentioned already). Preferably it would be in the base package (like "Baby Bauer" is now). David J.A. Clines' Concise Dictionary of Classical Hebrew would be a worthy add-on in that it would cover Qumran Hebrew as well as biblical Hebrew. Of course his multi-volume, super-expensive Dictionary of Classical Hebrew would be a real plus.
An expansion of the functionality of the Related Verses Tool and Phrase Matching Tool to allow for cross-version and mulitple verse comparisons would be helpful. I'd love to see a souped up version of this that would be similar to Accordance's INFER command. This would allow for searches for allusions and quotations across corpora. Right now it can be done on a verse by verse basis, but it would be extremely helpful to be able to compare Isaiah 53 to the whole New Testament or Ezekiel with Revelation, or James with Sirach, etc.
One thing that would be great would be some way of setting up an über-index of allusions and intertextual connections that could cross corpora. An xrefs file that could work with biblical texts, Apostolic Fathers, Josephus, Philo, Pseudepigrapha, or any other corpus of material would be extremely helpful. The index could work with references within BW, but it could also point to references outside of BibleWorks (e.g. Talmud, Mishnah, Midrash, etc.). What would REALLY be interesting here would be some means of making this a 'community built' list of allusions where folks could 'vote' on connections in the index or submit new connections if they think they might be there.
A way of expanding the syntax of the External Links Manager would be helpful (for instance, being able to have some kind of array that would convert different characters [like what represents an accent mark, etc.] would be helpful for going from bwgrkl to CCAT for Perseus searches, etc., as would the ability to send Unicode Greek to the web). It would also be helpful to have some means of converting syntax regarding book, chapter or verse number to different sites. So that if Gen 1:1 is represented somewhere as 001.01.01 the ELM could handle it.
Finally I'd love to see the ability to create one's own lexicon. Currently we can create versions, we can create CHM modules, we can even tag CHM modules to work verse-by-verse in the Verse Tab, but it would amazing if we could crunch our own lexicons as well.
The more LXX resources the better
Second that. Especially Muraoka's Greek English Lexicon to the Septuagint (2010: though very pricey, I'm afraid) which would be more than welcome (as an add-on or whatever), as would (and has this been mentioned before?) NETS: The New English Translation of the Septuagint.:p