I know this probably belongs in the Suggestions forum, but as PBB is currently still under development for 4.3 I think it might get quicker attention here, and it could possibly be addressed in the current wave of work:
There's a whole category of PBBs that could be built up out of pieces from other books in one's library. PBBs will work faster than clippings and have some capabilities that clippings don't have. I for one have been using a clippings file to keep a global table of contents of the whole Early Church Fathers series, but it is woefully slow. I'd like to make a PBB out of it. However, it will be a daunting task to create all the tagging necessary in Word. What I'd like to be able to do is copy/paste from the TOCs in each of the volumes into Word using a new "Copy as PBB source" option, which would automatically convert all the links in Logos into appropriate syntax for links in the Word doc, so that when it's compiled back into a PBB they work as links. How hard would this be?