[Moderators Note: This sticky thread is only for posting links. Please do not add any posts unless they have a link to a useful article/book. Thanks, --MMC]
I know this is a bit off-topic but thought that the value might make up for it.
Here is a link to a list of free online electronics publications:
http://tangentsoft.net/elec/reviews/free.html
Lots of very good books/guides to download.