Check these Links out for OS development:
(got them from google ;-))

www.nondot.org/sabre/os/articles
www.visopsys.org/osdev/
www.gaztek.org/osdev/
ftp.simtel.net/pub/simtelnet/msdos/info/ [addsig]

the first and the third are the best ones. [addsig]

Also try droping eye in thease pages:
http://www.oingo.com/topic/10/10819.html
http://osfaq.com/
http://www.osnews.com/comment.php?news_id=141&offset=25&rows=42
http://www.nondot.org/sabre/os/articles
http://tunes.org/Review/OSes.html
http://www.acm.uiuc.edu/sigops/roll_your_own/

Links:
http://members.home.net/bitrake/
http://www.execpc.com/~geezer/johnfine/
http://www.azillionmonkeys.com/qed/os.html

Programing:
http://www.rpi.edu/~laprej/personal.html

Forums:
http://www.mega-tokyo.com/cgi-bin/yabb/YaBB.pl?board=OS_FAQ&action=messageindex&start=20
http://os-dev.isa.net.au/boardindex.phtml

Projects:
http://www.rocklyte.com/athene/
http://www.visopsys.org/osdev/index.html#SOURCE
http://chaos.freeos.com/
http://personal.inet.fi/cool/menuetos/
http://www.geocities.com/the_real_sz/
http://www.savaje.com/products/savajexe.html
http://www20.brinkster.com/hang3r/new/easyos.htm
http://www.0reality.com/cgi-bin/ikonboard/ikonboard.cgi

And of course design lessons:
http://www.iarchitect.com/mshame.htm

Thanks a lot guys! I'll eye these sites sometime .

I have a big list:

http://www.osdever.net/
http://www.gnu.org/software/grub/
http://phantom.urbis.net.il/bphantom/OS_Design_Qs.html
http://my.execpc.com/~geezer/os/index.htm

There's a great project at http://www.trinary.tk/ or http://www.sourceforge.net/projects/trinary [addsig]