A great way to bring some different cultures into the class is to substitute  a few songs you normally would sing with your students with a few different childrens songs from other countries. Or translate a song you already sing to a different language as something special for the kids (http://babelfish.yahoo.com/  has a wonderful translator). This way your students get a taste of a different language without changing a lot of their set daily schedule.

http://www.mamalisa.com/?t=eh  Is a great site to get started on finding some new songs!