Taiwan

FarEasTone has a prepaid iPhone-supported unlimited data plan for about NT$1500 (as of mid-March 2010) for two months. No voice or SMS plans required. Works all over Taiwan with GPRS in rural areas and 3G in city areas (most of Taipei City, Kaohsiung, Kenting, Hualien, etc.). If I remember correctly, a valid Taiwan national ID is required (please correct this if you know more).