If you think the cost of mobile data plans in the United States is too high, try taking your phone on a trip outside the country. If you don't have an international data plan, on most carriers, you can expect to pay roaming fees as high as $20 for 1MB — the size of just one large Web page. Some carriers offer international data plans, but those aren't a great price either. Verizon, for example, charges $25 per month for 100MB if you're already signed up. T-Mobile provides free, unlimited international data, but at 2G speeds so slow (0.1 Mbps) you'd be better off having someone at home print out your emails and snail mail them to your hotel.
If you're traveling abroad, you can usually buy a local SIM card with plenty of data for $10 to $15. Just make sure your phone has a GSM-capable radio and is unlocked for international use. Most carriers will unlock your phone for use abroad, though many phones can take international SIMs right out of the box. You can also rent a Global hotspot with unlimited Internet from Xcom Global for $15 a day. The company will mail you an appropriately configured hotspot before you leave, along with a return envelope.
More: 10 Best Android Smartphones