This Java-based freeware synchronizes files and folders, even across network drives. Light but lacking any personalization features, Directory Synchronizer is an early beta but looks promising.
As befits a program possessing such a small footprint--the EXE doesn't require an installer, since it's only 22KB--there's not much to this app. Directory Synchronizer can be set to sync based on either date or content, accessible via the Sync menu. You can preview two folders that you're thinking about syncing with the Compare tool, and simply check off a box to exclude a subdirectory from the process.
Users can also save sync tasks and use them again with the "Open sync task" tool. Provided that the folder names and locations on their respective drives haven't changed, this should work without a hitch. Synchronization is reasonably fast: Syncing more than one gigabyte of files from a network drive to a local hard disk took about five minutes.
Certainly, there are larger and more powerful sync freeware tools. But if you're looking for tiny, free, and effective, and don't care about the interface, you should give Directory Synchronizer a look.