Firstly, cut down on your 'buy for' list.
I stopped buying for my sisters or their children and they for me - we were just buying each other crap stuff we didn't want - it was a shared decision that we'd rather spend the money on our own kids, and it was a real relief. 8 less people to buy for! I don't really buy for friends either. If you drop a hint, you might find that some of your your 'buyees' would be pleased to mutually agree to no exchange of gifts this year - the credit crunch is a perfect excuse.
Secondly, go 2nd hand for littlies, they couldn't care less. Ebay and car boot. I got DD stuff to the value of £300 last year for £50.
Thirdly, start early, start now. 4 or 5 paydays to spread it over, bollocks to the moaners who are posting a biscuit whenever they see the word 'Christmas' in a post in August. They probably are on a squillion pounds a year and will have it all delivered giftwrapped on December 23rd in a big John Lewis van 