My sister pointed this out to me. Rev. Dr. David Clipson is a Presbyterian missionary in Guatemala who keeps in touch with the world through his blog. He only appears to post every week or two, but each post is substantial. Unfortunately, the website host doesn't always seem to think he's a member and takes his site down.
This is a good example of how the web and blogs in particular can be used in the mission field. We are especially interested because my sister spent a year as a missionary in Guatemala and is leading our 2007 NWMC Summer Service team there next summer.