Batch Docs - Replace text in, add or remove content, and edit thousands of Word documents in doc and docx formats, PDFs, RTF documents, and other text documents.
mat2 - mat2 is a metadata removal tool, supporting a wide range of commonly used file formats.
regexxer - regexxer is a nifty GUI search/replace tool featuring Perl-style regular expressions.
Attribute Magic - AttributeMagic.com - utility to change file timestamps and metadata
Doxillion - Download fast and easy to use document file converter for PC or Mac. Convert Word, Doc, Docx, PDF, WPS, ODT, TXT, RTF, WPD, HTML, XML, word perfect and more source code file types. Freeware for home use.
GroupDocs.Metadata for .NET - GroupDocs.Metadata for .