General relief effort:
Japanese Red Cross Society: Please send your donations via a bank transfer.
The Red Cross has already launched efforts in Japan. Visit Redcross.org or text REDCROSS to 90999 to donate $10 from your phone.
GlobalGiving.org: Has launched The Japan Earthquake and Tsunami Relief Fund
Salvation Army personnel are organizing efforts in Tokyo and will soon send a team to help the severely damaged city of Sendai, Japan. To contribute to earthquake relief, text 'JAPAN' or 'QUAKE' to 80888 to make a $10 donation or visit SalvationArmyUSA.org.
Doctors Without Borders/Médecins Sans Frontières (MSF) is sending two three-person teams to the Iwate and Miyagi prefectures in Japan. To learn more about the organization's efforts or make a donation, visit Doctorswithoutborders.org.
MercyCorps is gathering donations for its overseas partner, Peace Winds Japan, which currently has personnel on the ground distributing emergency relief in Japan.
Save the Children has also responded. The organization is currently organizing efforts and donations to its Children's Emergency Fund will support outreach.
International Fund for Animal Welfare will be deploying a team to assess needs regarding animal rescue. They are encouraging support through donations, which will be used to buy pet food, veterinary supplies, vaccines and other necessities for animals needing help.
Fandom-specific relief efforts:
Cika: Is offering $10 sketches and $30 colored pieces.
SlifertheSkyDragon: Is offering dragon sketches for $10.
AtomicSmile: Is offering $5 commissions with proof of a donation.
List of Japanese Entertainment Industry (anime/manga) earthquake/tsunami survivors: Janime
Google's People Finder
Emergency Earthquake information in English: Please retweet this if you have people in Japan on your feed.
help_japan : A general fandom community where you can offer fannish works in exchange for donations.
Yu-Gi-Oh-specific offers at help_japan
American Cosplay Paradise: Is donating for those who upgrade regular members to celestrial accounts until March 18th. They have donated $965.00 at the time of this posting.
How to donate using Nico
If you have any additional information or are offering to donate your services, please leave a comment.