FAR

Product: FAR
Website: http://findandreplace.sourceforge.net
Type: Free
Requirements: Windows XP/Vista/7

FAR is a simple tool for search and replace operations over multiple files. You can apply ordinary "word by word" replacement, or choose to use fully featured regular expressions.
FAR automatically creates backups (unless you deselect this option) and is designed to operate on files dispersed over entire directory trees.

For your comfort you may define search strings that span multiple lines by just typing multiple lines - no obscure construct like "$\r?(?s:.)^" is required.

FAR has been created out of the need to change the layout of a website with hundreds of html pages. While all editors know "find and replace", and many support regular expressions, there is only a few that allows to:

Change a selection of files from different directories at once.
Allow search (and replace) patterns that span multiple lines.

Features:

Find files using a set of filters.
Replace file content over a collection of files.
Rename files quick and safely.
A comprehensive help, including a detailed regex manual.
A comprehensible user interface, not too simple, neither littered with checkboxes.
Viewer and editor to preview any changes or to quickly correct some last minute finding.