Expensive but cool.

http://www.boxedapp.com/

BoxedApp SDK is a developer library that provides a set of functions for
emulating a file system and a system registry for an application. Using
these functions, you can create virtual files, fake registry entries, keys
and values.

BoxedApp Packer is a developer utility that "packs" your original
application into a single all-sufficient executable binary. ActiveX
controls, dynamic libraries, and just all kinds of files that your original
application depends on - all can be "squeezed" in that file. The packer
creates an individual work environment for the application - with a
registry, swap file, etc. So, when the application runs on this - in a sense
- virtual machine, it doesn't require any external resources or special
privileges.