Have you considered selling them at a book store? We have this chain called "Half-Priced Books"....you just take the books in, they give you whatever they give you, and away you go. Might not get as much as a return, but, it is done and over with in one fell swoop. Also, many public libraries accept books for donation...you can write it off your taxes...senior centers? Shelters?

For me, it is way more important that I get this crap out of my house then the money end of it! (Not that I can't use more money...but, the feeling of ridding my house of something I know longer want/use/need is priceless!!)