I just got sent about 30 files to add to a website by a client. The files where full of spaces and bad characters for file names on the web. I found the following bit of software which has a whole bunch of features, which let you batch edit file names on your Mac.
It seems that you can use the software as a trial and then I think the price tag was $10, which I will be happy to pay.
Name Munger is a powerful, yet simple-to-use batch file renaming utility. Simply drag one or more files or folders onto the Name Munger icon and you can easily add text before or after the existing name, change one or more occurrences of part of the name or even remove some of the name. In a snap you can rename dozens or even hundreds of files.
Name Munger Can be downloaded here.