Virtual T is a TRS-80 Model 100/102/200 emulator that runs on Windows, Linux, and Macintosh. The goal of Virtual T is to provide 100% hardware emulation so any existing programs will run. It also adds powerful development and debugging tools.
xacc.ide is a opensource IDE aimed at mainly .NET development. It has a code editor written in 100% C# code, which is faster than most commercial offerings.
HackC is an extendable language translator that translates HackC files into C. HackC features are 100% customizable, so the feature list will grow over time. The HackC core language is currently in development. All inputs welcome.