FileSeek from Binary Fortress is a compact, fast, flexible, and free desktop search tool that can match Regular Expressions, Full Strings, and Any or All Words, including wild cards; search subdirectories; and include and exclude items from queries. It integrates with context menus in Windows, and it doesn't use indexing so it leaves nothing behind when you close it.
FileSeek's plain but efficient interface includes Search, Options, and file list sections in the main view. Searches start by specifying a Path, either by entering it directly or using the Browse or Browse and Append buttons. We selected our Pictures library, specifying .jpg files in the Include field and excluding .gifs, .pngs, and other image types by separating multiple entries with a vertical bar (which is often called the "pipe" key). We entered a term to search in the Query field and selected Treat Query as a Regular Expression from a drop-down list that also offered options to Match Full String, Any Words, or All Words. Under Options, we selected Search Subfolders (the default option) but left unchecked the options for case sensitive queries, to only show the first result for each file, and to process the results using File Handlers, which can slow the search process. We clicked Search, and FileSeek quickly scanned the selected directory, returning results in a list view that displayed not only File, Path, File Size, and other typical categories but also Line # and even the Line itself in a slender window running along the bottom of the main view. Right-clicking any entry let us open, copy, or delete it, and even open it directly in Notepad or a third-party application we could specify. Right-clicking files or folders in Explorer let us select Search with FileSeek from their context menus. We opened multiple instances of FileSeek simultaneously with no problems.
FileSeek is easy to use but powerful, and you can make some complex searches with it. There's no Help file, though, so if FileSeek seems a bit confusing or outside of the normal Windows user experience, we'd suggest sticking with the built-in tool or sampling one of the many automatic search solutions out there. If you want a fast, flexible, old-school tool that can find what you're looking for and you don't mind being a bit more specific about it, we heartily recommend FileSeek.