Thanks to everyone for their submissions. I've come to the conclusion that the only *reasonable* way to make this a truly useful resource is to allow people to add information to the database.
The reason is that Habanos SA is constantly changing box codes... and without someone on the inside who can provide a constant and comprehensive list of the factory associated with each box code (and the years with which that box code was used), it just won't be any more useful than the static lists that are abundantly available already.
I still intend to finish the pre-2000 box code decoding, which is quite trivial to do... but he's what I think needs to be done for the post-2000 box codes.
You enter a box code, it decodes the year and month... and if the factory code is in the database, it prints out the known info. If the factory code isn't in the database, anyone visiting the web site can add:
a) The factory associated with this box code (if known -- most of the time it isn't)
b) If the factory is NOT known, the user can enter the brand and vitola of cigars associated with the box code
In this way, we'll be able to constantly build a reference list of what cigar brands are coming from what factories during specific years. Even if the factory isn't known, it'll be useful to know the cigar brands associated with particular box codes from particular years.
Certainly there's a chance that bad data can enter the database in this way (fake box codes for instance), but the majority of the box codes entered will be valid, and thus the aggregate information will be useful.
I don't know when I'll be getting around to implementing this, but you no longer need to let me know about box codes that don't match... because I'll be changing how that's handled.