This used to be the thing I struggled with most until I developed my three-pronged attack.
Throughout the year, I keep an eye out for things that "scream" to be given to someone. Even if it's small, if it's thoughtful and clearly personal (and no, monogrammed Post-It notes don't count), people appreciate the effort and will most likely love whatever it is you've selected. I set aside a drawer in my home for these gifts and tape people's names to the packaging to make sure I don't forget who they're for. You'd be surprised how easy this is to do six months down the line!
Beginning on Black Friday, I browse for luxury items that are way on sale. This is a great time to stock up on basics—like a gorgeous, cashmere throw or leather gloves—at rock-bottom prices. These make for beautiful gifts that are as stylish as they are affordable and are easy to give to people you know well—but maybe not well enough.
I also make a point of getting to a few sample sales throughout the year. You can usually find choice items at drastically reduced prices, though it's important that you only buy for people whose size and taste you are familiar with.
If it's the last minute and you still have nothing for your neighbor, a homemade gift is as lovely to give as it is to receive. A friend of our family's makes caramels that are so sinful they should be illegal and wraps them individually in waxed paper tied with ribbon. If you're a baker, try making snowflake-shaped sugar cookies decorated with blue or white icing. They can be beautifully detailed and packaged in cellophane paper to be given individually or by the basket. Tins of Christmas cookies are fun in general.
Homemade jams, chutneys or sauces are always nice too. My dad loves to crunch on nuts, so this year I've mastered a wonderful spiced nut recipe from the Sally Clark Cookbook to give to all my male relatives.
If you're more of a craftswoman, try making jewelry or knitting a scarf. You know what you're good at, and I'm sure there are plenty of things in your arsenal that people would pay good money for. Harness that creativity and make a truly personal gift—you might even save yourself some loot!