"Toward the Tithe and Beyond," a sermon by pastor John Piper of the organization Desiring God, and "God's Plan for Giving" by pastor John Macarthur of Grace to You are both messages on tithing. You can find these messages on desiringgod.org and gty.org.
Piper wrote "Toward the Tithe and Beyond" in 1995 with his two eldest sons in mind. They were both grown and out of home, so he wished to admonish them toward tithing their earnings. Macarthur wrote "God's Plan for Giving" in 1975 to remind his parishioners that the way they handled their money in life was an indication of the degree of Christian stewardship in their lives.