Diffident is a coloured side-by-side diff viewer and editor that works in a terminal:

http://sourceforge.net/projects/diffident/files/
To compare two files:
diffident file1 file2
To run the tests:
diffident --test-slow
For full usage information:
diffident --help
Help - SHIFT-H
Quit - q
Move left/right - h/l or Arrow Keys
Move up/down - k/j or Arrow Keys
Select line up/down - K/J
Next/Previous - n/p or F8/F7
Page up/down - ,/. or PageUp/Down
Select page up/down - </>
Scroll left/right - z/x
Copy left/right - [/]
Insert line - a (Adds a line above the selected line)
Delete line(s) - d
Save changes - s (Saves the file containing the cursor)
Check out from git:
git clone git://diffident.git.sourceforge.net/gitroot/diffident/diffident
Browse the code:
http://diffident.git.sourceforge.net/git/gitweb.cgi?p=diffident/diffident;a=tree
Andy Balaam <axis3x3 at users dot sourceforge dot net>
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