Known .Net Languages

.NET IL Assembler Serge Lidin's book - .NET IL Assembler
Ada Ada
APL Dyalog APL
AsmL AsmL is the Abstract State Machine Language for .NET
CAML Microsoft Research F#
Cobol Fujitsu Cobol
Delphi Borland Delphi
Forth Delta Forth
Eiffel Interactive Software Engineering Eiffel for .NET
Fortran Lahey/Fujitsu Fortran for .NET
Fortran Salford FTN95 for Microsoft .NET
Haskell Hugs98 for .NET
Lisp DotLisp - Lisp dialect for .NET
Lua Lua.NET embedded scripting language
Mercury Melbourne University Mercury Project
Mixal Mixal for .NET
ML Standard ML from Microsoft Research
Mondrian Mondrian for .NET
Nemerle hybrid functional/OO language for .NET
Oberon ETH Active Oberon for .net
Pascal Queensland University Component Pascal
Perl ActiveState Perl Dev Kit with PerlNET
PHP PHP_Sharp compiler for .NET
Prolog Compiles Prolog to C#
Python ActiveState Python for .NET Research
RPG ASNA Visual RPG
Ruby NetRuby interpreter
Ruby Ruby/.NET Bridge
Scheme Tachy (Scheme-like) language
Scheme Indiana University Scheme.NET
Smalltalk SmallScript from SmallScript LLC
Smalltalk #Smalltalk compiler

Source: GotDotNet.com