For the tech-savvy traveler that doesn't want to spend thousands of dollars on data roaming charges, the best option is to go prepaid when traveling abroad.
The best deal in France if you have an unlocked iPhone is to buy a prepaid "SFR La Carte" sim card. They have a €24 plan valid for 20 days with unlimited data and €10 calling credit.
One of the best deals in Germany is blau.de which offers a €9.90 plan with 1Gb of data valid for 30 days or a €19.90 plan with unlimited data valid for 30 days. Blau sim cards can be purchased in supermarkets and can even be activated while roaming outside Germany!
