When the original Monstrous Manuals were released for the second edition game they consisted of loose sheets of paper which were placed into binders so that only the monsters that you required needed to be taken with you. They ended up releasing quite a few of these loose leaf packs. The idea was that the first compendium had the binder, and when they released the next two, you just inserted them into the binder in alphabetical order. The third (or was it fourth, I believe it was the Dragonlance one) also had a binder, and that was so that one binder did not get too big.
Each of the monsters took up one page, though the problem that arose was that each sheet generally had a monster on the front and one on the back, so when you got a monster that would fall between those two monsters (alphabetically that is) the order would be thrown out. I thought it was a clever idea, however while it worked for a while, they ended us scrapping the concept and going back to the book form (which is basically this book).
I sort of liked it through, but what I ended up doing is scrapping the binder and buying my own binders so you could put the pages into plastic sleeves. Initially I tried to have them all in alphabetical order, but as I mentioned, it ended up not working, so I simply put them into the particular settings that these monsters were related too, so what I would do when I took them to games (the games where never at my house as I lived pretty much on the city fringe, and one of the players simply never wanted to leave his house, so it was basically either at his house or we wouldn't play, so in the end we ditched him and played at a roleplaying club in the city) I would take the standard compendiums and any world specific compendiums that I needed. Oh, and if a module was released that had a new monster in the back (or Dragon magazine released an issue with monsters in it) I would photocopy the monsters and add it to my 'special' monster folder. That is what I really liked with the idea of one page one monster.
Obviously things have changed though and they have gone back to the old standard with regards to the Monster Manuals. This book did try to capture all of the monsters available, and maintained the one page, one monster style. The other problem with the loose leaf sheets is that they had pretty poor resale value since they would deteriorate quite quickly (and with the early ones having perforated strips that made using them and keeping them in good condition particularly hard indeed).