It sounds like you might have a better feel for this than me. I just send what's requested. For the books, she hasn't asked for any for herself (she always wants DVD's and videos though) but I've made great friends on the book websites sending kid's books for the last 3 years. Also, my S-I-L is always wanting the latest Clancy etc. So, Amazon, ebay, halfbay and others have their address in memory.
I used to get books, videos, local papers, sometimes just a surprise treat that I probably COULD have bought there but wouldn't necessarily have bought for myself (bath stuff or candy, for example), sometimes things to decorate my room and my desk (Mom knew I wouldn't think to brighten the place up, so she helped!), clothing...can't even remember what all. I almost didn't care WHAT she sent, though...just getting a package from home made me feel less isolated.