I noticed an entry on "Gratitude" by Douglas J. Schuurman (pp. 342-343) in the new Dictionary of Scripture and Ethics, edited by Joel B. Green (Baker Book House, 2011). It briefly outlines various philosophies about the concept but emphasizes that gratitude or thankfulness for the Christian is bound up in his acceptance of salvation which is a gift. There is no tit for tat, so to speak when discussing this gift. Schuurman identifies obedience as the true response of a grateful person.
In her book, Traveling Mercies, Anne Lamott identifies the core of all our prayers to God: "Help me, help me, help me." and "Thank you, thank you, thank you."
Count your blessings, indeed.