Hitoshi Doi's Seiyuu Database

Comprehensive database with photos, voiceography, discography (with CD cover scans), articles, interviews, events and index of available merchandise. Database searchable by genre, title, or actor. [Japanese and English]
http://www.tcp.com/doi/seiyuu/

Anime Voice Actors/Actresses

Extensive list of Seiyuu links.
http://www.asahi-net.or.jp/~AE5T-KSN/anime/voice-e.html

Seiyuu Enterprises

Fan clubs for Hayashibara Megumi and Mitsuishi Kotono. [English and Japanese]
http://www.seiyuu.com/

Seiyuu Directory

Tribute to Japanese voice actors. Includes features on selected Seiyuu with pictures, profiles, history, commentary, and links.
http://www.geocities.com/seiyuu_directory/

Perry and Ansatsusha's Seiyuu Page

Voiceographies with images of the anime characters.
http://www.perryandtsua.com/Seiyuu/

Ryu's Seiyuu Infos

Database with character images and seiyuu galleries.
http://www.seiyuu.info/