I just donated a few more books.
While doing so, I noticed the site says this is a 503 charity, which means that donations are tax-deductible, allowing the government o pick up part of the bill for anyone who itemizes.
Reading through the requests, there was one funny one, asking for The Virtue of Selfishness, saying: "In the 21st century there are a growing number of people who have no food, home, or even clean water. And sadly, with deep pockets, huge houses fancy clothes and yet are ignorant of the sufferings around them. In order to further enlighten myself on how to be more kind i want to read this book." (The requester says he's in 7th grade)
The site has almost 950 requests since Jan of this year (they prune older ones).