Relief and aid:
Google peoplefinder tool. They also have crisis response information up.
Things to consider as you donate. It breaks down what's best, when, how to tell who's reputable, and where to report sites that pop up asking for donations that seem to be fraudulent.
Yes, Japan is asking for aid - the Gizmodo article about texting the redcross was updated.
Shelterbox: people are going to need shelter more than just about anything else.
Redcross: that page allows you to specify where you want your donation to go. You can also text REDCROSS to 90999 to donate $10 from your phone.
Doctors without borders: they're generally some of the first folks on the scene at disasters such as this, and they always need help and donations
Save The Children has set up a fund specifically for earthquake/tsunami relief.
International medical Corps: you can also text MED to 80888 from any mobile phone to give $10.
Huffpo has a roundup of other aid links.
CNN: video round up and live blog.
Shakesville: roundup and open thread.
Streaming video. (Japanese)
NOAA: Modeling of the earthquake and tsunami. There's a larger version of the video at Gizmodo.
BBC: What happened at Fukushima Daiichi.
Big think has more information on the nuclear plant incident, including a video
EERI: history of Japan's recorded earthquakes
USGS: how earthquakes work (for kids) - also information for adults.
More information on what causes tsunamis.