Free Opener is a comprehensive file viewer that allows you to open more than 75 file types: documents, videos and audio files, images and more.
Unsurprisingly, many of these are formats that you can view and play now, anyway: HTML, JPEG, PNG, WMV, AVI, MPG, ZIP, assorted plain text variants, and so on.
However, Free Opener can also handle many Office documents: DOC, DOCX, XLS, XLSX, XLSM, PPTX, PPT, and PPS. Graphics support includes the ability to open Photoshop PSD files and many RAW file types. And it can also display email formats (EML, MSG), Flash animations (SWF), archives (7z, ZIP, RAR, GZ, TAR, TGZ, JAR), PDF files, even source code formats (VB, C, CS, JAVA, JS, PHP, SQL, CSS, ASPX, ASP).
The program isn't just a viewer: a few file types allow you to go just a little further. So if you open a RAR archive, say, then you're able to extract selected files, and after opening a PHP module you're able to edit it. The editing options are basic in the extreme - Windows Notepad provides more functionality - but this may still be useful.
Please note, Free Opener installs multiple components to assist in its work, including the K-Lite Codec pack and .NET Framework Client Profile. You don't have the option to install these or not, so if you'd rather keep complete control of the codecs on your PC then it's probably best to give this a miss.