I do this as well. I keep a index file with the monsters I have created, sorted alphabetically by type (or name, if a "named" NPC), and I jot initiative down in my binder as they are called out. Rolling for my mobs, I sort the cards while the first player is acting (writing this down may slow things down a tad in the beginning, but I find it a nice reference).
Then again, I also have magic items written on color-coded index cards like Monte Cook proposed, have loot that hasnt been identified on regular white cards, and spell-effects that the players are under (such as Bless, Prayer, etc) written on smaller purple index cards so the players dont keep saying, "Oh yea, add one to hit for Bless...and oh yea, add one to damage from the bards song, and...oh yea, I get one more from Prayer". That gets old really quickly
Kealios