Considering that I have what I think is a great resource for the build up to your mission trip, I hesitate to put this link, but I think these books look pretty cool. They are a series of 3 journals from Standard Publishing that are for use before, during, and after your mission trip. I haven’t ordered them or anything, but they are look like a really cool idea.
You can check them out at http://www.standardpub.com/Books/Young%20Adults/journals.asp
Also if you want a custom mission trip journal send me an email and we can talk about making a "Creative Prayer" journal just for your trip.