■ Browse into documents saved as compressed archives (JAR, DOCX etc)

There are many document types using compression to minimize their size. For example all modern office document formats (DOCX, XLSX etc) are really little ZIP files where MS Word and Excel store the text and pictures. Java JAR format is another crypto-zip format and so are NSIS installers (.EXE), and probably many more — PBIX anyone?

File managers like windows explorer and xplorer² can browse into .ZIP archives to examine the compressed files therein. So theoretically they should be able to read into JAR and DOCX "archives", and read the contents that make up a Java program or a Word document. I am not sure why anyone would want to do this, but let's assume that you actually want to peek inside, and move on with the demonstration :)

A possible use could be searching for something by name inside a pseudo-archive

One way to make this happen would be to edit the registry where document types are declared, and make JAR and DOCX behave like ZIPs, e.g. make HKCR\.docx point to CompressedFolder type, just like ZIPfolders. This will make such documents folder-like browsable, but then it would be harder to open them with their native application, say Microsoft Word.

xplorer² ultimate edition offers a different path for those that wish to enter disguised zip files without altering the default type associations, through Total Commander WCX plugins. If you install something like Total7zip you can enter JAR and the like with File > Enter archive menu command. Using WCX plugins with xplorer² isn't very difficult if you know how to do the association, and here are the detailed steps:

Download xplorer² TC plugin helper (if you don't have it already)
Download Total7zip plugin and unpack it
if you can't open RAR archives download 7zip or xplorer² compressed archive namespace extension
Use xplorer² WCX helper to connect Total7Zip with xplorer² (watch the demo video for details)

You only have to do this once and then you can browse into all sorts of interesting files like JAR, DOCX, even xplorer² installer!

ps. To any orthodox readers out there, happy easter / Χριστός Ανέστη!