Ask HN: Any good SIM-only carriers or plans in US?

Do you already have a phone? Sounds like you do, just checking.

If you walk into a T-Mobile or an AT&T Wireless store with a phone in hand, the salesperson can work with you. I recently checked this out for a development (unsimlocked) G1 running a friend's custom build of Android. I wanted just data service (no voice except emergencies). Did not want a contract.

The T-mobile person was happy to help, but couldn't give me an exact price until we'd run through the system. Said would be between $30-$50 per month. The AT&T person was also happy to help, but he cautioned that AT&T doesn't support the G1 and if anything happens I would be on my own. They were asking ~$35/month IIRC. Again, this is for data only -- voice is extra.

If you just want voice and not data, you can always buy a prepaid phone, then throw away the phone and take out the SIM card. That's actually what I'm doing with the dev G1 right now while I weigh the data options. I have an AT&T GoPhone prepaid service, works fine for voice.

T-Mobile will sell you prepaid service at $100 per 1000 minutes/SMS messages, or pay-as-you-go for $30-40 per month without a contract. I have service for my G1 via the latter option, which costs me about $75/mo. with unlimited data and more calling minutes than I can conceivably use.

My experience has been that most carriers will happily let you sign up for some sort of prepaid service without a contract, as long as you don't expect hardware discounts.