SourceGear | DiffMerge | downloads
DiffMerge is an application to visually compare and merge files for Windows, Mac OS X and Unix.
One feature also interests me
Folder Diff. Performs a side-by-side comparison of 2 folders, showing which files are only present in one file or the other, as well as file pairs which are identical or different.
Just downloaded and tried and it looks good
Could be great for keeping my external HD and Macbook and Desktop in sync