WordPoint

It automatically translates any word, in any application, at any moment, in any of the available languages -- English, Hebrew, Arabic, Dutch, French, German, Greek, Italian, Portuguese, Spanish, Russian, Swedish, Turkish, Czech, Polish, Hungarian-- without switching back and forth between your application and an external program.

All you have to do is to point with the mouse at the desired word. A small balloon will pop up over the word, containing its translation.