The San Francisco AIDS Foundation offers a marketplace/storefront from which you can bounce around to different merchants who'll sell you something and donate part of the proceeds to the Foundation. You can choose by store type and the resulting layout makes it easy to see which stores give the biggest amount to maximize bang for your holiday giving buck.
The Pink Ribbon Shop, in support of breast cancer research, is still open for business and they have ornaments for the holidays. If you order today and spend more than $75, you can get free 3-day shipping and actually get your purchase just in time for Christmas. We could just overdose on the pink!