Hikaru Midorikawa: Fansite has links to Hikaru's personal homepage [japanese] and information on his roles.
Hikaru Midorikawa Fan Club: Yahoo! Club devoted to the Seiyuu.
Hikaru's Bar: Created and maintained by Midorikawa Hikaru. News, a BBS, a favorite character poll, and voice samples. [English/Japanese]
Hitoshi Doi's Seiyuu Database: Provides information on voice roles, CDs, books, radio and events.
Midorikawa Hikaru WebRing: A webring for fans of Japanese anime and game seiyuu Midorikawa Hikaru, and his characters.
Midorikawa: The Greatest Seiyuu Ever: A Midorikawa Hikaru shrine. A profile, role information, CD listings, j-pop and EMU music files, links, and a birthday tribute.
Perry and Ansatsusha's Seiyuu Page: List of anime series, with character images.
The Midorikawa Hikaru Yahoo Group: The Emotional Intricacy of Characters. Homepage for the mailing list. Focuses on character discussions, information, pictures, sound files, links, and polls for members.