R'tzei, near the end of the Amidah. For me, it reflects the eternal plea of humanity for God to be there...just to be there. Followed by Hodaah, where we acknowledge and give thanks for God's ever-presence in some way in our lives, this one-two beat in the service humbles me almost to the point of tears--and sometimes beyond--every time. (I try to daven at least daily, and still, each time it blows me away.)