There's also a ton of free techie books at
IBM Redbooks library. From what I could tell, there's no registration required.
It's mostly IBM related stuff, but there is a lot of general IT as well.
If SOA/BPM is your game,
SoftwareAG has a free SOA and BPM for dummies books too! I don't have the URL handy, but I think you'll need to register to download.