@pierretong: Hey! Any idea how many minutes/texts/data per month you'd like? There are so many prepaid services out there to choose from. Have you looked at the following MVNO operators?
1. PagePlus Cellular (Verizon MVNO and therefore it has the best coverage area). Most Verizon phones can be put on this service and you're allowed to Bring-Your-Own-Device (using CDMA technology). In your case, you'd have to buy an android/droid phone without contract. Check eBay or Craigslist for good deals. The best plan they offer is their "TnT1200 plan" which for $30 a month which includes: 1200 minutes talk, 2000 texts, and 100mb data. They also offer unlimited and pay-as-you-go plans.
2. Straight Talk (AT&T MVNO). Offering one of the best Unlimited Everything (2gb data cap) plan a month for $45. The best phone to get is their Nokia e71 ($170 @ Walmart.com). Their Nokia e71 comes with a "open" sim card that you can swap into other unlocked or AT&T phones and use. However the sim swapping violates Straight Talk's TOS (but not enforced) and you end up buying two phones (must keep the e71 to keep the service)! So it's kind of expensive
3. PlatinumTel (Sprint MVNO). Probably the best pay-as-you-go service out there. Plans start at $10 for 90 days of service with rates being $0.02 a minute for talk; $0.05 per text; and $0.10 per MB! They also offer an Android phone for their service.
Hope this helps and you find the prepaid service plan that works best for you :-) Boo to contracts!