For DD's birthday, we did a combination of what J&K and shanado mentioned, and it worked out great. DH and I bought her one big gift from us, and that was it. Then after she got her birthday haul, we went through the mountain of toys. If there were toys - or clothes - that were really similar, I returned the duplicates for store credit. This was great because I used a lot of the store credit to buy her clothes that she actually needed for the fall and winter season.
We put away some of the toys in her closet, unopened, and I saved them to pull out on rainy days between her birthday and Christmas. This was a lifesaver since there were so many rainy days this fall!