MacMerger 1.0 - Quickly and easily merge two folders on your Mac.. (Free): "
MacMerger is the quick and easy way to merge two folders on your Mac. Simply select the original folder and the folder you would like to merge it’s contents with and with a single click of the mouse the contents are merged together. MacMerger is freeware meaning it costs you nothing for this great utility.
MacMerger copies the contents of one folder to another much faster than the OS X Finder does utilizing special copying routines. This is especially convenient when working with lots of small files or large amounts of pictures that usually take a very long time to copy using the Finder.
Mac OS X 10.5 or later
(Via MacUpdate - Mac OS X.)