atomo - very interesting language, very flexible and compact. I stumbled upon it because someone built a Mongrel2 Adapter for it. What is interesting about atomo for me is that it is yet another new language with prototype-based object orientation. Something that is tried far too rarely (other languages in this area are Slate, Self, Io, Newtonscript and JavaScript).

Also interesting: atomo is embedded in Haskell and thus provides a dynamic scripting language for Haskell environments and of course a good integration into the Haskell world. There was something similar with one of the first Perl6 prototypes, which was also built in Haskell (Pugs).