It would be very valuable for serious partnerships if BW extended the tools available for development of system or comparison. Just ideas I had in mind:
1) System notes tool (a big bonus would be if it can be exported or imported from and to common text editor).
2) Ability to compare answers to the same polls. For example I would love to be able to filter all questions that both me and my partner answered differently and review them. Or compare myself to some of the people on this site.
3) Bidding/lead challenge - style BBO challenges.
4) Bidding practice app/hands - something like Ubid (you get a hand, bid, send it to your partner - he bids when he can it is sent to you), but with ability to upload your own hands, and with ability to limit HCP range and distribution.
I believe that decent implementation of some of these can be commercialized, at least I would be happy to pay some low fee to use those features.
Plus... it's free!