Articles
If you are new to Japanese swords, these two articles I wrote are handy references (now merged into one). They seem to have been copied frequently throughout the internet either verbatim or loosely paraphrased at this point in time.
Most of my new articles are ending up in my blog now, but these two articles are essential reading for new collectors.
Sword and Smith Classification covers how we talk about smiths for school and era.
Sword Ratings Systems is more important, covering the different organizations that rate and attribute swords and what the ratings mean.
Some general reference stuff:
Recommended Books
My 2004 Japan Trip -or- Death by Envy for Sword Lovers
Educational and commercial links:

Japanese Swords of the Bizen Tradition
Bob Benson and I are collaborating on a series of books, featuring swords owned by North American collectors, with additional articles provided by past or present collectors and experts in our community.
Japanese Swords of the Bizen Tradition
The series will comprise several volumes, the first of which is Japanese Swords of the Bizen Tradition, which is currently available for purchase! Click on the book cover to the right for more information about the book and purchasing it.