Although being able to create zip files right in the Finder is very convenient, they have the disadvantage of often including invisible files. These can be handy on the Mac, but if you send them to people using other operating systems, e.g. MS Windows, they show up as a bunch of unusable extras, like .DS_Store, Icon^M and __MACOSX.
ZipCleaner can remove these files from the zip archives the Finder creates: just drop them on it. It also allows you only to remove the .DS_Store files, which contain Finder settings and Spotlight comments. To do that, drop an archive on ZipCleaner, while holding down the option key.