The Ark and Ark 2 are by the same guy and I've heard they are even better. I think I remember hearing that is actually his interest and he came across the Joe stuff by accident.
Bellomo's Ultimate Guide to GI Joe is great, but geared towards the figures with most of the background info available for the hey day years and not so much the later releases. His Totally Tubular 80's Toys book is also a great all in one book. Not overwhelming with depth but the quantity and quality is really good.
James Kavanaugh aka Kuukuuson also released the R.A.H.C. A Guide which covers the modern o-ring figures.
The JoeDeclassified guys put together convention magazines that are always packed with info. All the way to the right on their front page under JoeDeclassified Magazines are issues 0-4. Since they are pic heavy it might take a while for each issue to load. The latest one from New Orleans, which used International Joes as a running theme, hasn't been added yet.
http://www.joedeclassified.com/?page_id=98
