Originally posted by Mike Lush, then augmented by Keith Westcott.
You're unlikely to think about this until you need to, but there is no obvious way of searching within a bunch of files for text using a regular expression. I needed to search within thousands of .tab files to find those with that contained a common error in the name of the raster file (all the rasters started with numbers, but some of the tab files lacked them, showing only e.g. File "SP8955.tif"). I needed to find files containing the regular expression File "[A-Za-z][A-Za-z] so that I could correct them by adding the relevant number.
The tool I discovered for doing this is AstroGrep. This will allow you to select a directory and search for files containing text, allowing you to specify regular expressions. It's basically an extension of the standard Windows file search and a modern version of Grep for DOS. You can also specify a text editor for files of a certain type and open for editing directly from the interface.