Program: Karen's Replicator
License: Open Source
Description: Automatically backup files, directories, even entire drives. Karens Replicator copies selected files from one drive/folder to another. Source and Destination folders can reside anywhere on your network.
Options include repeated copies at intervals as short as a few minutes, or as long as several months, copy only files that have changed, and the replication of folder and file deletions.
New features allow you to specify which files should not be copied, and also which days a job should be skipped.
Website: karenware. com/powertools/ptreplicator.asp (official website bad link)
Other: I use it the program of 2 years, in my opinion it is the best program for synchronization.