I wish this book was required reading for everyone on my team and in my mission organization: Encountering Theology of Mission: Biblical Foundations, Historical Developments, and Contemporary Issues (2010). From Amazon:
This fresh, comprehensive text fills a need for an up-to-date theology of mission. It offers creative approaches to answering some of the most pressing questions in theology of mission and missionary practice today. The authors, who are leading mission experts, discuss biblical theology of mission, provide historical overviews of the development of various viewpoints, and address theologically current issues in global mission from an evangelical perspective. This readable yet thorough text integrates current views of the kingdom of God and holistic mission with traditional views of evangelism and church planting. It also brings theology of mission into conversation with ecclesiology and eschatology. Topics covered include contextualization, the missionary vocation, church and mission, and theology of religions. Sidebars and case studies enable readers to see how theology of mission touches real-life mission practice.
In addition, there is good stuff on the missional church, the relationship between social action and evangelism, spiritual warfare, and contextualization, all while staying focused on establishing “kingdom communities” among the nations. I really like the discussions of the historical developments of various viewpoints.