The Queen is a spiritual center for the United Kingdom. It's like having a president you really like for life now, since all of the govt. part is now handled by the House of Commons and the House of Lords and the PM, very much like we do. The Royals don't make law, but they influence, and 90% of the time in the right way, I'd say.
BTW, we as Americans really don't get to diss the Crown...some houses over there are older than this hemisphere.
Max