Regexxer is a cross-platform, graphical search/replace program written in GTK+2 with an interface similar to that of popular text editors. It provides a powerful set of features for manipulating regular expressions, which are used for the search and replace operations. It can be used to search for and replace text inside files and directories, as well as to perform various other text processing tasks. It also has graphical support for editing regular expressions, allowing users to quickly build, test, and debug their regular expressions. Regexxer includes a number of features to make regular expression use easier and more efficient. These include syntax highlighting, error detection, search and replace histories, and an expression builder. It can also be used to search for and replace text inside source code, HTML, XML, and other markup languages.
The discontinued official site has been replaced with few sentences of text without links thanking the last 25 years. The program can be safely downloaded from CNET aka Download.com.
Searchmonkey does not do find and replace, it only finds.