Everyone has pretty much hit on the same things we do (or are transitioning to doing), so I thought I'd highlight one area that hasn't yet been mentioned.
I no longer buy wrapping paper/ribbons, etc. for gift giving.
For family bdays, we just wrap our gifts in playsilks we gather up from around the house -- colorful, large enough to cover practically any item, and perfect for my younger kiddos who have trouble ripping open packages yet!
For bday party gifts/gifts to others, I've made up ribbon drawstring fabric bags out of leftover fabric scraps/clearance fabric in assorted sizes. Same deal for Xmas, except I've been building our Xmas fabric bag stash over the past three years (we have a lot of people in my family!
) -- I take advantage of after-season fabric clearance sales and then each year I sew up a dozen or so more assorted size bags. This past year, we finally had enough to do the whole holiday without paper!
FWIW, sewing up bags is VERY easy and quick, and they're so lightweight and easy to store until next year...