LibU is a multiplatform C library that comes under a BSD-style license. It includes many interdependent modules for accomplishing several tasks: memory allocation, networking and URI parsing, string manipulation, debugging, and logging in a very compact way, plus many other miscellaneous tasks. It has a small footprint (about 70KB for the default configuration), it is modular, and it has a multiplatform nature, making it an ideal candidate for embedded systems. KLone is an example of such usage.
pyrobase assembles general Python helper functions and classes that can be applied to any project. This includes some additional tasks for the Paver build tool, an improved xmlrpc2scgi module, unit test helpers, and generic base modules for various domains. All modules have unit tests, and the goal is to reach >80% coverage.
cmocka is a unit testing framework for C with mock objects. There are a variety of C unit testing frameworks available supporting different platforms and compilers. Some development requires a lot of different compilers and older versions, which makes it difficult to use unit testing frameworks. The idea of CMocka is that a test application only requires the standard C library and CMocka itself to minimize the conflicts with standard C library headers, especially on a lot of different platforms.
Thread Weaver is a framework for writing multithreaded unit tests for Java classes. It lets you create breakpoints inside your code and to stop individual threads when they reach a breakpoint. This allows you to produce controlled repeatable tests that can help to verify thread safety and detect race conditions.
ytest is a PHPUnit extension, based on the PHP extension "runkit", that allows you to replace static, private, and global functions with fakes, stubs, or mocks. This eases the automated testing of PHP applications that weren't written in a TDD fashion (i.e. test-first). It can also be helpful on projects where many methods are kept private, or projects that don't use OOP so much. ytest has already been used to "test after" (as opposed to "test first") some real-life commercial projects, and has proven useful. It needs PHP >= 5.2.