MirrorX
MirrorX is a simple tool that lets you create or update a mirror of a directory and it's contents.
For example:
MirrorX C:\MyPictures \\MyServer\MyShare\MyPicturesBackup
If you append a "-s" option, then MirrorX will show you what it would have done, without actually doing it.
There are various tools for doing this sort of thing, but I couldn't find any with the exact options I wanted; so MirrorX is that tool. I use it to backup my music and photos onto a removeable drive.
The source is available in the MirrorX Google Code project, and a compiled binary is available here.