Re-Sampling Photo Files -- in bulk

[FotoTejas]

Does there exist a program (preferably freeware or shareware) that does nothing but go to a given directory (or to flagged files w/i a directory) and re-size them to specified dimensions? For instance, "resample everything in this directory to be 400 pixels on the long side."

If not, is there more sophisticated image manipulation software that includes this feature?

Thanks,
Lee