Pay what you want for awesome ebooks and support charity!
Sale ends 13 days from this post.
Humble Bundle is well known to do these big bundle sales where they gather up a selection of materials and sell them for a short period of time with a steep discount. Simply pay at least as much as a tier costs to unlock it; otherwise you're free to pay as much as you want. You can even choose what percentage of your payment goes to which group involved (Charity, Humble Bundle and the Authors)
The top tier is unlocked with only $15 (around £11.49)
Note these are all "ebooks" so digital books to read not physical copies of the books.
Note 2 I've not read any of these, so if anyone has or buys into the bundle and reads up on them it would be great to hear your thoughts on the various titles.