Not  sure how long this will last, but Half.com is doing a promotion where if you spend $10 in product, you can get up to $25 free shipping. So no $3.49 shipping on a .75 book. :D

Great for hardcovers (got a bunch of Redwall hardcovers for $.75 each). But if you've been waiting for some books for quite a while here, you might be able to get them really cheap at Half.com during this sale then trade them in here for more!

Rather than re-explain it all, Slickdeals has a good writeup here:

http://slickdeals.net/f/4638060-25-worth-of-Free-Shipping-at-Half-com-min-10-purchase-Can-be-used-on-multiple-items-like-all-those-75-books