The CK-12 Foundation, which is a project to create open-source freely redistributable science textbooks for personal and professional use by kindergarten to high school teachers, homeschoolers, and interested other parties, is once again offering a new batch of them free in multiple venues.
You can get the lot
directly from their website, which mainly has PDF files for most titles, but also now has DRM-free
ePub and
Mobi for what I assume are selected "finished" works which have a stable, bugs-worked-out edition.
You can also get syncable versions free @
Amazon (available to Canadians; selected titles also available in the
UK) and
iTunes, according to a note on their website (I don't have iTunes properly installed on the netbook, so
someone else will have to provide a link or I'll edit one in later).
(ETA: I should add that these are very large, 20-100+ MB image-filled files and you should probably use the "Transfer via Computer" option for the Amazon version and try not to hammer the CK-12 site by getting them all at once.)
Titles include the usual maths, biology, chemistry, physics, engineering, etc. that you'd expect, but it also looks like they're branching out into history as well and have some Spanish-language translations of selected volumes. I've looked through some of these in the past and the information seemed pretty solid for the subjects I had some acquaintance with.
I hope their project succeeds, because basic science education (not to mention history) in many places could certainly be a lot better, or even existent at all.