WRITE 'hello, world!'.
One of the first exercises of every computer scientist is probably the claim to be polite and to greet the whole world.
There is a large list of possible expressions - and it grows and grows. But in most cases (ignoring some exotic / esoterical programming languages) the reader can understand the statement without knowing the language.
Anyway, whatever language you speak - welcome and hello!
10/2008: english translation started, but the german version remains the main language for now.