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.
Clojure is a dynamic programming language for the JVM. Note - current Clojure development has moved to Google code: http://code.google.com/p/clojure/ Project web site: http://clojure.org
a GCC compiler plugin and domain specific language ....
GCC-MELT is a high-level domain specific language to extend the GCC compiler. It provides several features (pattern-matching, first-class dynamically typed values, functional/applicative/object-oriented/reflective programming styles, Lisp-y syntax) MELT can also be used to explore the internal representations used by GCC (Gimple, etc...)
JazzScheme is a programming language based on Scheme. It is also a full featured development platform that has been used for more than 10 years to develop high-quality commercial applications.
LispSharp is a fully compiled lisp implementation for the .NET Framework. It uses a Lisp dialect similar to ISO Lisp, it has a Command-line toplevel compiler with Read Compile Print Loop.It references any .NET DLL and produces standard .NET assembly.