Ruby on Rails (http://rubyonrails.org/)

ColdFusion on Wheels (http://cfwheels.org/)

DOS on Dope (http://www.secretgeek.net/dod_intro.asp)

Haskell on a Horse (http://haskell.on-a-horse.org/ -- site seems to be down)

Cobol on Cogs (http://www.coboloncogs.org/ -- not actually real)

The $LANGUAGE on $NOUN naming convention amuses me. Any others I'm missing?