I need a diff tool that has a command line option to create and save a diff report that looks easy to read, something like the html report produced by WinMerge. I have a few hundred files that I need to compare and it's not practical to have to open the files and manually and save the report.
I did find a tool that does exactly that: http://sourceforge.net/projects/diff2html
It's a bash script that uses diff(1) and creates an HTML page from the output with colour-coded diffs.