Kind of like 'Everyone Else' or whatever that book of NPC's was for D&D?
Sounds like a good idea to me...I wouldn't buy it, but since the other product did well that a modern version might sell ok.
Not to hijack the thread, but why would you pay to get a book full of NPC's? They're not that hard to create by hand, and generally you change a few things (like feats or skill selection) around anyways.
What would make you actually spend good money on a book that just has NPCs? What would make it 'stand out' enough for you to actually purchase? For me, I guess it would have to have some cool new equipment (as someone else said), and some interesting combinations of how to achieve a certain type of character that may or may not have a specific AdC of PrC made for them.
Of course, AdC's and PrC's (and feats as well) are already a dime a dozen...how many 'more' do we really need? Most of them are the same as something else, with maybe one skill switched in/out...