Niue is a tiny, embeddable stack language distributed as a Java library.
Niue is under active development. To use the latest version of Niue, checkout the code from github:
git clone git://github.com/vijaymathew/niue.git
Follow the instructions in the INSTALL file to build the code. For your convenience, a pre-built jar file can be downloaded here. The file name will contain the date on which it was built. You may want to rename it to niue.jar before using it.
Niue - A Guide and Reference. [pdf]