Meld - Mac Port - This is actually Meld itself ported to Mac.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.
AptDiff - AptDiff is a visual text / binary files comparison and merging utility for Windows.
WinDiff - Download Windiff : free files and folders comparison tool
Araxis Merge - Home of the award-winning Araxis Merge two and three-way file comparison (diff) and merging application, Araxis Find Duplicate Files, Araxis Replace In Files, and the Araxis Ketura issue tracking, project scheduling and time tracking application.