When writing anything that needs to communicate with a terminal in some way, it is almost always speaking some dialect of VT100 or ANSI. The libvt 100 library aims solely at parsing a stream of VT100/ANSI data and then letting the host application do the rendering. Many other projects also parse VT100/ANSI data, but their parser is always tangled up with the actual rendering of the data, making reuse in other projects problematic. The hope is that other projects will start using libvt100 and everyone can stop reinventing the wheel with each project.
Apache .NET Ant Library is a library of Apache Ant tasks that support development for the .NET platform. It supports Microsoft's frameworks as well as Mono. The library contains tasks to run common .NET development tools like NUnit, NAnt, or MSBuild. In addition, it contains a task to create Windows MSI installer packages using the WiX toolkit. The "old" .NET development tasks of Ant's core have found a new home here as well, and further development of those tasks will happen inside of this Ant Library.
AsDoclet can be used to generate Actionscript and C# files out of Java sources. Such a tool is useful for RIA and client/server applications where value objects are transmitted between server and client as serialized data that should be deserializable on both ends again. That includes remoting technologies like Flash Remoting, RTMP, Blaze DS, Red5, and Hessian.
TCRun is a tool written by software engineers in QA to help in writing, managing, and running automated test cases. The current version is written in C# for use on Windows, though other versions / platforms may be created later as necessary. It tries to make writing automated test cases as simple and painless as possible. It includes support for NUnit exceptions, logging (both test case specific and framwork/runtime), parameterized tests, test case resource files, and a validation framework. It can be used in mono, but is somewhat untested (it's actually built by mono, and it tests itself).