It's easy to brag about how many languages your only-works-on-our-highly-customized-server application uses. What about an application meant to run on lots of computers for use by ordinary users.

I present to you the application I love to hate: lilypond

• lilypond's own music typesetting language
• c++
• guile
• postscript
• tex/latex
• python
• shell/make
• metafont
• vim scripts, emacs lisp scripts
• texinfo
• html/css
• flex

Count the paradigms too: traditional, functional, stack-based, scripting, declarative, and various specialized languages.