Just wanted to shout out a positive recommendation for xcomglobal (www.xcomglobal.com
Just back from my trip to Germany. I rented a mifi cellular wifi router for the week. Verizon's roaming data plan is insane now, so I opted for this instead. It cost me $15 a day, which sounds expensive but its comparable to renting hotspot access at the hotel or hotspot locations. I plugged it into a fairly large usb battery pack so it would stay charged pretty much all day and just left it turned on in my backpack. That gave my android phone, and tablet, my laptop, my ipod touch, and my kindle all the access they needed all the time.
It worked just as was advertised. I'll use them again.