With AT&T and probably others, you can get a rechargeable card for refills at 7-11 or Walmart. Text the card number from your phone the first time. Take the card back where you bought it, add money with cash and the refill happens without any further action.
The AT&T phones can be activated over the internet. Find a wireless hotspot somewhere and use a laptop.
Originally Posted by GneissGuy
for better security, use an internet cafe, or sometimes higher end car dealerships have open computers for customers waiting for repairs.
No logins etc required, just go in like you are getting your car worked on and jump on real quick.
Using a laptop from a hotspot requires you to either 1) use you existing ISP, in which case the fact that you where at a hotspot is mute, or, 2) use an account setup with that hotspot provider, in which case you have usually paid with a CC or given up personal info.