You can have other languages other than English, Spanish or French as long as you have a 1-1 translation of any non accepted languages to an accepted language. A common way ive seen this is at the top right of the page have links to the same page but a different language, ie
You have page Index.php thats in Lithuanian and one in english
You put Lithuanian files under /li/ and english under /en/
then for each page in in the li, have a link at the top pointing to the en version,
You can look here for an example(they use flags to show the language)
http://www.dofus.com/en
Someone will stop by that can unsuspected you soon.