Products that "bottle" applications inside the operating system are more popular than ever. Let it start with products like HDGuard or Dr. Kaiser DRIVE and let it end with something along the lines of Citrix.
For practical use these solutions are a little impractical though; I often need on-the-fly sandboxing for applications. That's where Sandboxie comes in pretty handy: The program is a simple to use but powerful Windows application that enables the user to bottle applications inside a sandbox, monitor the changes and delete these changes afterwards (or import them into the real filesystem, whatever you like best 🙂 ).
It really works great and adds a lot of practical use cases for testing or monitoring. The tool is shareware, most of the features work in the unregistered version.
If anyone has a similar free tool (open-source would be perfect, I'd like to peek into the code 🙂 ) feel free to comment (oh please do!).