Have a separate worship service for the children. This way, the whole service can be geared to them, including the songs, the Bible readings, the prayers, etc. This idea does detract from the ability of the parents to model worship for their children, but then it is can sometimes be more meaningful to the children because everything is at their own level of understanding. Most sermons, particularly those that are textual rather than topical, can be illustrated using stick figure cartoons. Pastors can encourage children by speaking to them during the sermon, applying the text in ways that are applicable to them.
Worship leaders have songs that include verses for just the children.
For example, in a certain song have the children sing one part while the adults sing another part. The Lord's Supper is an excellent opportunity for the children. This is where a parent can really bring the Gospel to the child. A computerized database of all the songs plus a notebook of all the songs. As many of the Touching the Father's Heart CDs as possible.