New York Aikikai: home base for Yamada Sensei and headquarters of the
United States Aikido Federation

Aikido Online: sophisticatd site with lots of info and products.

The Aikido FAQ: an introduction to Aikido, an explanation of the Principles of Aikido, an introduction to general Dojo Etiquette and training,
an Aikido Dictionary, a bibliography, anecdotes and other fun Aikido material.

Aikido Today Magazine: contains a Dojo directory as well as lots of Aikido links.