Agent Ransack is a tool for finding files and information on your hard drive fast and efficiently. When searching the contents of files Agent Ransack also displays the text found. Users can then quickly browse the results without having to separately open each file!
grepWin is a simple search and replace tool which can use PCRE regular expressions to search for strings of text within files. grepWin adds an entry to the shell context menu to easily search selected folders.
dnGrep allows you to search across files with easy-to-read results. Search through text files, Word documents, PDFs, and archives using text, regular expression, XPath, and phonetic queries. dnGrep includes search-and-replace, whole-file preview, right-click search in File...
AstroGrep is A Microsoft Windows GUI File Searching (grep) utility. Features include regular expressions, versatile printing options, stores most recent used paths and has a "context" feature which is very nice for looking at source code.
Ack is designed as a standalone (one perl file) replacement for 99% of the uses of grep. ack is intelligent about the files it searches. It knows about certain file types, based on both the extension on the file and, in some cases, the contents of the file.
Search & Replace Master is a freeware. It looks through multiple files for a string or pattern and can also replace it with another string or pattern.