From its earliest days, the church based its praxis on the Bible and saw witnessing to Jesus as its purpose. Thoughts from the second half of Acts 1.
Though Jesus was actually sending a community into the world, his words in the Great Commission often have been used as the rationale by which churches send individuals into cross-cultural settings.
Reading the Bible Missionally has some excellent articles and students of the Bible and Mission will find much that is helpful here. However, I'm not convinced that the book hangs together as a whole and it is of little interest to the more general reader.
Messianic and missional reading of the Old Testament - that's what Jesus instructed his disciples to do. We have been fairly good at the first, but pretty lamentable at the second.
One of the major challenges facing mission in the future is the interface between southern and northern mission.
Whatever their strengths as a style statement, fig leaves are not suitable as working clothes; they don't offer much protection from thorn bushes (I'm not speaking from personal experience, I hasten to add).
The Word of God cannot be understood apart from the cultural and linguistic situation in which it was originally given.
Yes we have to obey Christ's command at the end of Matthew's Gospel, just as we have to obey all his commands. But the Bible's story of mission doesn't start and end there - and nor should ours.
The Israelites leaving Egypt did not have advanced degrees in theology but God didn't hesitate to tell them all kinds of in-depth and complicated things about himself.
Links to some good stuff that you may have missed.