Admittedly, this is a particularly easy year for me.
DPs proper gift was sorted months ago, as she wanted Bon Jovi tickets, so was online at 8am manically refreshing in October for them, and sorting out a hotel. So all she's getting on Christmas itself is a stocking with some small stuff in it, and tickets for a musical for the same weekend as Bon Jovi, which isn't until September so there's no rush buying them.
DD is 18, and wants a new phone, but doesn't really care what, so I'll research and buy that on Wednesday, probably off Amazon or Argos. Then again, a stocking with some tat in it. DP has got her some clothes and smellies etc.
Niece and nephew will involve a trip to the toy shop on Wednesday. I've asked my brother if there's anything they want, and he's been useless as per usual. So I don't need anything specific, and an entire toy shop to choose from.
The rest of my family do a sort of secret santa thing, so I've only got SIL to buy for, and we stick to around £25.
DP buys for her family, so nothing to worry about for me there. Although they do play a game between Christmas and New Year that involves buying around 6 presents, but each tends to be about a fiver, and then they get dished out according to a complex rule set. These are all quite jokey things though, so again nothing really specific to get.
And then theres only one friend that I exchange presents with, but I already know the book I'm buying her this year, so just need to pop into Waterstones.