In Jewish communities—especially at the synagogue—Hebrew is enormously useful, because the prayer books are all in Hebrew, as are most of the blessings (all, that is, apart from those from Aramaic, which is written in Hebrew characters). People also like to pepper their emails or conversation with the occasional Hebrew word.
Non-Jews—particularly Christians—appear to be inordinately impressed when you tell them that you know Hebrew (especially when you can read and write it), because it strikes them as the equivalent of someone saying that they can read Homer in the original Greek, or Cicero in Latin. (This admiration is entirely unwarranted, of course if you were raised in Israel.)
By far the greatest benefit, however, is being able to read and appreciate the Hebrew Bible in the original. Useful? Not much, in this day and age—but extremely gratifying.