The first time I used wikipedia to look at revisions I was quite impressed by the colored two column output indicating which bits had changed. Working mostly on the command line, it's been frustrating that diff can't do better than two column output. Even colored diff and cdiff only color lines by whether they're from the left or the right, not whether they're internally different. Python's difflib can create the wikipedia-style two column colored output, though, and with a bit of modification can print to the console with ansi escape sequences:

jefftk@host ~ $ python icdiff.py text_A text_B
This is an unchanged line	This is an unchanged line
This is a line with a speleing error	This is a line with a spelling error
This line was deleted
Whitespace     shows up where critical	Whitespace shows up where critical
But it's not     shown when not	But it's not ugly when not
	And here I go, adding a line

And the usage:

  usage: icdiff.py [options] left_file right_file

  options:
    -h, --help           show this help message and exit
    --cols=COLS          specify the width of the screen. Autodetection is Linux
                         only
    --context            print only differences with some context
    --numlines=NUMLINES  how many lines of context to print; only meaningful
                         with --context
    --line-numbers       generate output with line numbers
    --show-all-spaces    color all non-matching whitespace instead of just
                         whitespace that is critical for understanding
    --print-headers      label the left and right sides with their file names
  

Improved Color diff: icdiff