http://www.mahjongg.com/ is the web site of a particular piece of Windows software (for
four-person Mah Jongg), but also has a lot of Mah Jongg-related
links.
Computer solitaire Mah Jongg
Eddie Kohler's
xmahjongg is an implementation of Mah Jongg solitaire for X Windows and
Unix/Linux, with configurable tilesets and layouts. Its home
page is
http://www.lcdf.org/~eddietwo/xmahjongg/.