To get the headers right I'm killing this thread and starting a new on, please let this one die

Great stuff. I particularly like the price list link. I've not had time to study it closely but wonder if you find it matches fairly well with existing KAP costs?

Some of the ones I use;

Culture, Myths and Legends of Cornwall (http://www.connexions.co.uk/culture/index.htm)

Mysterious Britain & Ireland (http://www.mysteriousbritain.co.uk/)

Real world relics (http://www.kingarthurbanner.com/artifacts.htm) (The extremely detailed items listed have made great trinkets for my PC family heirlooms.)

Early Medieval Kings and Lost Kingdoms (http://hefenfelth.wordpress.com/early-medieval-kings/)

I like! Please post more :)

Well, this should be a given:
le morte d'artur (http://www.sacred-texts.com/neu/mart/)

Maybe we should do a proper meta-post? With headers and stuff?

The Historic Tale Construction Kit: http://www.adgame-wonderland.de/type/bayeux.php

Have some fun with a little personal abuse of the Bayeux Tapestry.

http://gotmedieval.blogspot.com/
The blog of a Princeton grad student, focusing mostly on silly things in medieval manuscripts (this week's feature: medieval penis trees)

http://www.nipissingu.ca/department/history/MUHLBERGER/blog.htm
The blog of a professor at Nipissing University, who does a fair amount with chivalry.

http://www.nipissingu.ca/department/history/muhlberger/froissart/tales.htm
From the same guy, a bunch of excerpts from the Chronicles of Froissart, focusing on the more swashbuckling episodes.

http://willscommonplacebook.blogspot.com/
The blog of a historical reenactor and amateur historian who does a lot of great work with chivalric subjects, including data on weapons and tons of translations of primary sources. I know some people are skeptical of the SCA, but this guy really knows his stuff.

http://medievalnews.blogspot.com/
Medieval news--the latest on whatever medieval ruins are being dug up, what's making big waves in the exciting world of medieval academia (England's paleography program may be discontinued! This is really really bad, not kidding), etc.

medievalists.net (http://medievalists.net) and deremilitari.org (http://deremilitari.org)
Websites with a whole lot of primary sources and academic journal articles that you ordinarily would not be able to read without access to an academic library or several very expensive subscriptions; the latter focuses heavily on medieval military history.

http://houseoffame.blogspot.com/
The blog of Geoffrey Chaucer--I WILL CONTINUE SPAMMING THIS LINK UNTIL THE INTERNET GOES COLD AND DEAD SO HELP ME GOD

http://www.themorgan.org/exhibitions/exhibOnlineThumbs.asp?id=OnlineKings
The Morgan Bible: also known as the Macjzk-something Bible, this was commissioned for the court of the great crusader king Louis IX (or VIIII if you want to be authentic about it). Positively gorgeous illuminations, including some awfully gory fight scenes.

http://bestiary.ca/beasts/beastalphashort.htm
A medieval bestiary.

http://diglit.ub.uni-heidelberg.de/diglit/cpg848/
The Manesse Codex--another medieval manuscript with lots of pretty knightly illuminations.

http://www.scribd.com/doc/281970/Secrets-of-the-Satanic-Executioners-2nd-edition
Secrets of the Satanic Executioners-- THIS IS GARBAGE THAT MAKES DAN BROWN LOOK LIKE UMBERTO ECO. I HAVE READ MOST OF THIS AND NOW MY MIND IS INDELIBLY POLLUTED WITH SOME OF THE STUPIDEST GODDAMNED NONSENSE EVER FARTED OUT OF A MAN'S BRAIN CONCERNING THE MEDIEVAL PERIOD. DO NOT REad this

http://www.inthemedievalmiddle.com/
A blog run by several academic medievalists, including J.J. Cohen, a former student of the writer on chivalry Richard Kaeuper; it often goes off the deep end of academia, probably unusable for the purpose of running a Pendragon game, but I'm sure there are things in there that would be useful.