FreeSoftwareBooks.com
the name says it all

Home Page  |   Languages   | Java/J2EE    |  Microsoft    |   Unix/Linux    |   Computer Science    |   Databases    |  Web   |   Networking  
Operating Systems 
Operating System (by Dang Van Duc, et al) Operating Systems Lecture Notes (Martin C. Rinard)
Practical File System Design with the Be File Sysytem (Dominic Giampaolo)
A Short Introduction to Operating Systems (M. Burgess) Write Your Own Operating System [Resource] [1] [2] [3]
Programming the Be Operating System (Dan Sydow) Operating Systems Introduction (B. Brown)
Lecture Notes of Operating Systems (by Fikret Ercal) [by Arm El-Kadi]
Implementing CIFS: The Common Internet File System (Christopher R. Herte) [PDF]