T-Mobile has stepped in with an offer that can hardly be refused by anyone looking to travel abroad: Free unlimited international data and texts in over 100 countries. If you are traveling anywhere that is pink below, then you can open up your e-mail and look at Google Maps without fear. It won't cost you anything extra.
There are a few caveats: The free texting is to US number only. No tethering. Speeds are limited to email and maps, so no 4G for free. You need to have an international phone. There is also some language that some places still charging if there are additional taxes, which is not well described on the website. You also need to sign up for their "Simple Choice" plans, which actually aren't bad at all: $50 is the entry point with unlimited talk, text, and data with no contract (You have to bring your own unlocked device or buy one from them at full price... which is often a better deal than the subsidized handsets you get from other companies). Still, this takes a lot of the pain out of international travel and staying in touch. A tablet, like the Nexus 7, combined with a plan like this would be an ideal solution for just about all of your travel needs.