Historical Needlework Resources - has links to all kinds of extant pieces of needlework, including a number of examples of brick stitch. They also have a great write up on the Goss Vestments
A Stitch Out of Time - the article that started it all. Great analysis of the V&A bags
Medieval Silkwork - a blog about all kinds of medieval embroidery, including patterns for 2 brick stitch bags in hard-to-get-to (at least for me) collections
Joyce Miller's Embroidery - charts for two brick stitch projects, a box and a cushion. The cushion is quite similar to a book cushion in V&A and charted out by Master Wymarc (see A Stitch Out of Time, linked above), so similar it took me awhile to figure out they weren't actually the same. I wonder if they were worked by the same person or in the same convent? Very curious and interesting.
Brick Stitch Box This is a photo taken from a book in German. The same stitch pattern is on the alter hanging at the Met in New York.
Medieval Arts & Crafts - a lovely blog by another A&S 50 challenger, whose challenge is to chart out 50 brick stitch patterns! This is a great resource if you are looking for pattern ideas, though not all of them are 100% straight-off-the-artifact documentable. She does tell you how she derived the pattern though so you can pick and choose whatever will work best for your projects documentation needs.
Blackwork
Ensamplario Atlantio - a free PDF e-book collection of blackwork filling patterns. Gotta love free patterns! There are 220 or so individual designs so this should be very useful if you do a lot of blackwork.
Resources and Supplies
Needle'n'Thread books and links page. There is a fantastic list of online shopping resources, which is great if you live in an area with few or no embroidery specialty shops. She also has a great book list, including some online books.
Hedgehog Handworks - wonderful resource for hard-to-find embroidery and costuming supplies, including several kinds of silk (including filament) and metal threads. The prices are good and the service is excellent.
Needle in a Haystack - has a great selection of needlework silks and actual photos of all the threads so you can get a better idea of color! Yay for that! Those color cards as expensive, especially for Au Ver a Sois.