Searching Japanese Databases
There are a number of Japanese websites that hold in their databases large numbers of prints by various artists. Invariably they can only be searched using the Japanese language. Guidelines for how to do this in Internet Explorer follow. Other browsers work in a similar fashion.
[These guidelines have been made as simple as possible to accommodate all abilities. Power users - please don't feel insulted ;-)]

Your browser needs to be able to recognise and display Japanese characters
Test this by going to Yahoo! Japan. If you get the page displayed using something other than obviously Japanese characters try choosing 'view' then 'encoding' then 'Japanese (auto-select)' from the menu in IE.
If this doesn't work you'll need to go to Microsoft Update and get the appropriate update.
Support for Firefox users here.
Support for Opera users here.
Further help from the National Diet Library.

You need to input the artist's name using Japanese characters
These are available at Toshidama or The Kunisada Project.
Highlight the Japanese version of the name you're interested in, right-click and choose 'copy'. The name will have to be pasted into the appropriate field in the database search page.
Caution - Searching for Hiroshige also brings up prints by Hiroshige II and Hiroshige III.

How to search the datebases
National Diet Library
Tokyo National Museum
Hagi Uragami
Tsubouchi Memorial Theatre Museum, Waseda University
CII Pilot Electronic Library Project (Login as 'guest' and no password) [Bilingual - just follow the links.]
Boston Museum of Fine Arts

Other Japanese websites
Google Japan
Yahoo! Japan

English language databases
Fine Arts Museums of San Francisco
MFA Boston