Which MNer is going to find a dropped shopping list that says Zig Lora and try to decode it? 
Bathroom stuff. Make sure you're not going to run out of: loo roll, toothpaste, lady's necessities 
, handwash.
Kitchen stuff: washing up liquid, binbags, foil/baking paper/clingfilm, washing up sponges, scouring pads, Marigolds (in LARGE size too so the men can't wriggle out of helping!), dishwasher tablets, microfibre cloths, Vanish for the inevitable stains.
General: batteries batteries batteries, candles, lighter/matches.
A friend has a box (printer paper box from work, so decent size) that she covered years ago in wrapping paper. As her dc unwrap stuff, she checks the wrapping for any extras (instructions, gift card, funky pencil or what have you) then chucks the paper in the box. When you look at photos of her dc, they aren't being photobombed by a black binbag! Genius.
Keep in a drawer with all other the handy stuff (batteries, matches...) bottle opener, screw drivers to open pig-awkward battery compartments in toys, scissors to cut off plastic tags...
Where people write tags for dc's gifts, write what they received on the tag and keep them together. Much easier when writing a thank you card - or a whatsapp message, or via Skype etc - to be able to say "Thanks Aunty Jean for the Tardis slippers" rather than something impersonal and generic.
Oooh i'm getting excited for Christmas! I have been prepared for a week and i am dying to see ds open his gifts!