Horodruin is a tool that allows file/folder content analyzation and synchronizing for the purpose of keeping them current.
The simple but very functional interface lets you easily work with multiple folders (2 or more) and adjust the analysis to suit your specific needs. There are also a few different filtering options that can be applied and are based on files mask, access-rights, file sizes, and others. And you are permitted to limit copy actions via the use of those filtering options.
Horodruin includes an optimal file multi-threaded copy engine (by temporary file and/or by overwriting files), a minimal registry usage (only for Explorer integration), and HTML Help is included. This tool is generally for advanced users only so keep that in mind.