Interjections, the little words like 'oh' and 'hm', carry a lot of meaning in oral communication in all languages. How often do we focus on them in our teaching? For German, I recently read the poem empfindungswörter by Rudolf Otto Wiemar. It impressed me with its simple juxtaposition of various interjections with the words 'the Germans'. It really has to be read aloud with appropriate intonation for full effect.

empfindungswörter
aha die deutschen
ei die deutschen
hurra die deutschen
pfui die deutschen
ach die deutschen
nanu die deutschen
oho die deutschen
hm die deutschen
nein die deutschen
ja ja die deutschen

Relevant links that might be of interest:

• The Wiktionary collection of German interjections and  Wiktionary collection of English interjections are good starting points. To find this in other languages, go to the main page of the Wiktionary in that language, and then look for an index of categories.
• The Canoo page on interjections has information and examples in German.
• The German Wikipedia article on interjections has even more information.
• The Goethe Institute lesson plan 'Was ist deutsch?' incorporates the poem by Wiemer.