The following links may be helpful for Operating Systems development

http://www.cs.utah.edu/flux/oskit/
http://www.cs.utah.edu/flux/oskit/doc.html
http://www.cs.columbia.edu/~kamra/teaching/4118.spr05/OSKitN.htm
http://directory.fsf.org/wiki/OSKit
http://www.cs.utah.edu/flux/oskit/html/oskit-www.html
http://bochs.sourceforge.net/
http://sourceforge.net/projects/gazos/
http://gd.tuwien.ac.at/languages/c/programming-bbrown/advcw1.htm (BIOS)
http://www.arl.wustl.edu/~lockwood/class/cs306/books/artofasm/Chapter_13/CH13-2.html (BIOS)
http://en.wikipedia.org/wiki/BIOS
http://en.wikipedia.org/wiki/BIOS_interrupt_call
ftp://ftp.embeddedarm.com/old/saved-downloads-manuals/EBIOS-UM.PDF
http://en.wikipedia.org/wiki/Master_Boot_Record
http://en.wikipedia.org/wiki/Partition_(computing)
http://home.arcor.de/wzwz.de/wiki/interrupt/i13_en.htm
google: bios programming language
http://www.minix3.org/
http://minix1.woodhull.com/
http://www.kernel.org/ (linux)
http://www.freertos.org/
http://code.google.com/p/testoskernel/
http://crocos.sourceforge.net/
http://forum.osdev.org/index.php
http://wiki.osdev.org/Main_Page (wiki)
http://en.wikipedia.org/wiki/Executable_and_Linkable_Format
http://www.minoraddition.com/2011/04/01/dissecting-executable-and-linking-format-elf/
http://users.csc.calpoly.edu/~mhaungs/archive/paper/node10.html (ELF)
http://www.nasm.us/
http://www.intel.com/content/www/us/en/processors/architectures-software-developer-manuals.html
http://www.fermi.mn.it/linux/quarta/x86/index.htm (i386 instructions)
http://www.cs.ucla.edu/~kohler/class/aosref/i386/toc.htm (i386)
http://www.letterp.com/~dbg/
http://pdos.csail.mit.edu/6.828/2011/readings/pcasm-book.pdf
http://cis.csuohio.edu/~somos/asmx86.html
http://www.hackchina.com/en/cont/192246*
http://david.carybros.com/html/device_driver.html
http://geezer.osdevbrasil.net/johnfine/index.htm*
http://geezer.osdevbrasil.net/johnfine/index.htm#sample*
http://wiki.osdev.org/JLoc*
http://gazos.sourceforge.net/*
http://pdos.csail.mit.edu/6.828/2007/labs/lab1/lab1.html
http://pdos.csail.mit.edu/6.828/2007/
http://ocw.mit.edu/index.htm
http://os.inf.tu-dresden.de/l4env/doc/html/loader-internal/elf-loader_8c.html
http://books.google.com/books?vid=ISBN020163208X
http://en.wikipedia.org/wiki/B-tree
http://code.google.com/p/high-concurrency-btree/
http://en.wikipedia.org/wiki/Sleepycat_Software
http://en.wikipedia.org/wiki/Berkeley_DB
http://www.wotsit.org/
http://www.computer-books.us/assembler.php
http://www.ipdatacorp.com/mmurtlpd.html
http://www.ipdatacorp.com/mmpd.html
http://www.linuxjournal.com/article/1059
http://web.mit.edu/gnu/doc/html/binutils_12.html#SEC15