[elemeno]

Lulu? At least that's the only place I've specifically bought a PDF - then I found out that it's wrapped in some horrible Adobe DRM (if there are any ways to remove this, I'd love to know). I don't begrudge the money, I just wish I could read it in Preview.app rather than Adobe Digital Reader or what ever it's called - it doesn't scroll smoothly, only page wise which is a massive pain when there's lots of diagrams.

Other than that, all the ebooks I've bought from individual storefronts, often from having seen them on HN, have come as a PDF/epub/mobi bundle to work on any device.

[donatzsky]

Install Calibre and then follow the instructions here: http://apprenticealf.wordpress.com/

If it's not DRM protected, but rather a "secure" PDF, you'll need some other tools that can remove the owner password. About.com has a list here: http://pcsupport.about.com/od/toolsofthetrade/tp/pdf-passwor...

[jwn]

Please don't password protect PDFs for books. It makes it a huge pain in the ass to actually read. I'd much rather you do what the Pragmatic Bookshelf does and just embed our name into the PDF.

[ConstantineXVI]

As far as I can tell, O'Reilly doesn't even do that. I've even strings(1)'d them and found nothing.