I wanted to diff two files. One of them needed some seds on each line and sorting. I wanted to do that on the fly, without leaving a massaged in­ter­me­di­ate file lying around.

colordiff --unified <(cat orphaned_permalinks.txt
                        | sed 's@http://www.georgevreilly.com/@@'
                        | sed 's/.aspx$/.html/'
                        | sort)
        links.txt | less -R

• Use process sub­sti­tu­tion—<(cat | sed | sort)—to generate one argument to colordiff. The other argument is simply links.txt.
• The first sed is using @ as the delimiter rather than the more usual /, since the pattern contains multiple slashes that would otherwise need to be escaped.
• Pipe the colored output into less -R (aka --RAW-CONTROL-CHARS).