Here's a list of programming languages I consider promising and/or interesting (mostly front-edge research languages).

 

Nemerle
www.nemerle.org
Strong type-inference engine.
Syntactic macros (ala LISP) for flexible language extensions (Meta-Programming).

 

Boo
http://boo.codehaus.org/
OO, statically typed, syntactic macros, Python-based Syntax, .NET integration.

 

F#
http://research.microsoft.com/fsharp
ML / OCaml for .NET. Interesting functional mix. Type-safe. Scripting.

 

SML.NET
http://www.cl.cam.ac.uk/Research/TSG/SMLNET/
Standard ML for .NET

 

Comega
http://research.microsoft.com/comega/
C#-extension to support concurrency and work with XML.
Has interesting concepts, like Haskell's infinite lists, which is good for continuations etc.

 

SpecSharp
http://research.microsoft.com/SpecSharp/
Specification oriented (compare: Eiffel), design-by-contract, pre- and post-conditions etc.

 

IronPython
http://www.ironpython.com/
Python for .NET

 

Epigram
http://www.e-pig.org
Dependent typing. A very innovative Code-Editor. Very powerful compile-time checks.

 

Ruby
http://www.ruby-lang.org/
A pretty expressive OOP scripting language.

 

Haskell
www.haskell.org
No comments.

 

Python
http://python.org/
An interesting OO scripting language.

 

Smalltalk
http://www.smallscript.org/
http://www.squeak.org
The OOP language. Dynamically typed.

All .NET languages
http://www.dotnetlanguages.net
http://www.dotnetpowered.com/languages.aspx

 

History of programming languages
http://www.cerezo.name/archives/img/history.html

 

Language creators
http://www.angelfire.com/tx4/cus/people/

 

 

Now THIS is a fun way to navigate presentation slides:

This is a fruit from the tree of ZUI - zoomable user interfaces.

 

P.S. I like these non-standard interface approaches, like for example IUI - inductive user interface. Computers are capable of wonders of user interaction, we programmers just don't always have enough imagination to discover new ways.

I had to learn how to create MSI installations using WiX. Pretty nice stuff.

 

If you want more on this, let me know.