WhoGaveMeWhat is an iPhone app for remembering who gave you (or your family) what gift, and whether you’ve thanked them yet.
More convenient than a spreadsheet or a piece of paper. You can also quickly attach photos from the camera or photo library to remind you which novelty socks were which. Or add a photo of yourself wearing that new dress. Or your baby sporting the ridiculous hat— Then send the photo of the gift to the person who gave it.