OSDev.org

Does anyone know of a site that will describe the structure of a particular file type. You know like pdf, wmv, iso, zip and such. This would be very useful for creating built in programs for your computer.

http://www.wotsit.org/ is a good one.

http://www.google.com/ is a great site that I find particularly useful, but seems to be underused. Maybe not many people know about it...

Perhaps a bit over-sarcastic, but

This is also a good read: http://www.osdev.org/phpBB2/viewtopic.php?t=14961