1)   NZB Editor 1.0
Nzbedit is a free GUI editor designed to let you edit the contents of an NZB file. You can change the fields of the NZB including the subject an author fields. You can do searches and replaces, delete parts or segments, etc.

 2)   NZB File Validator 1.0
Nzbval is a free utility that you can use you test an NZB file against your news server and verify that all of the parts exist before you start downloading. It can save you a lot of time because you can avoid downloading from bad .NZB files.