I’ll do my best to offer what the Reformed tradition can offer to this discussion.  "We" seem to be getting some bad press because of Calvin-ism, which is different than Calvin himself. 

Content:

What distinct kinds of things should the emerging movement share?  That’s tough.

Faith: not an assent to doctrine, but trust in our heavenly Father as shown through Jesus Christ and witnessed to by the Spirit.  Trust is the key word and worthy translation of "pistis."

Scripture: the Word of God is not the Bible but Jesus Christ.  Where we find witness to the Spirit of Christ in Scripture we have encountered the Word of God.

Salvation: Faith in Jesus is not a simple belief, but trusting that he is the way into eternal life.  In as much as we walk in Jesus’ steps we have "already" experienced salvation in restored God-human, human-human, and human-creation relationships.  However, we have "not yet" been saved.

Solidarity: charity is one thing, but developing relationships with the poor and outcast is another.  Calling for solidarity would be a call to suffer with (compassion) those in need.  This would be a less patronizing form of mission and better capture Jesus’ words to "take up the cross."

Ritual: baptism and Lord’s Supper need to be recovered in more relational and conversational ways.  For example, keep the historic words of the Lord’s Supper, but make it more a meal and hospitable gathering.  We need more creative, relational rituals and celebrations.

Theological Method:

The reformed tradition seeks to "semper reformada" or always reform.  Of course, this reformation or transformation takes place according to the Word of God, which is not necessarily the Bible.  According to Barth, it is first the person of Jesus Christ.

Calvin also offers the "internal witness of the Spirit."  The truth of the Scripture is not found in reason or argument, but by the Advocate within who testifies about God’s Word.  Discovering God, then, is done in a communal conversation centered on God’s Word through the traditional Christian practices (Lectio Divina, contemplative prayer, hospitality, sharing meals).

It seems to me that our theology ought to arise out of this kind of always reforming context and focus on the god shown forth in Jesus Christ. 

Purpose:

Again, Calvin commented that the three OT roles were fulfilled in Jesus: prophet, priest, and king.  As Christ’s body, we should enter into those same roles.

Prophet: Speaks for God as he/she confronts the powers and principalities, identifies false idols, condemns injustice.  May even speak against the church.  Speaks for humanity as she/he repents and pleads for God’s mercy.

Priest: Sanctifies the community of God; makes them holy.  Identifies what distinctive qualities of God’s people set them apart.  And provides the methods of atonement.  In our case it may have more to do with pure hearts and forgiveness.  However, this does not discount the importance of ritual (i.e. baptism and Lord’s Supper)

King: Ensures justice; especially for the poor, oppressed, widow & orphan.  I imagine this to be the Christian voice in governmental arena.  Works to make gov’t as much God’s servant as it ought to be.

As for what motivates us, I borrow from Calvin once again: gratitude.  In as much as we have already entered into the abundant life we can be grateful.  Someone as described evangelism as one beggar sharing with another where to find bread.