Comment Re:The US market is really confusion (Score 1) 75
I've often suggested TracFone to my various European friends when they visit. It's a GSM reseller that sits on top of AT&T's network, so you get widespread national coverage, and it's extremely cheap. You can buy a phone (which usually includes 20 minutes of service to start with) for as little as US$10. You can refill the minutes via a telephone number, their website, on the phone itself through menus, or by going into most any store and buying a 'minutes card' (TracFone's minutes cards can be found in almost any grocery and convenience store or gas station, and most any consumer store that has an electronics section). Much like Steve's suggestion, going into a physical store is the easiest when using a foreign credit card (and it's the only way to buy using cash), but since such a WIDE array of stores sell their cards it can hardly be called an inconvenience.
The other primary reason I suggest it? Privacy. Sure, your two existing phones may work with T-Mobile's or AT&T's networks (their 2G/GSM networks work with most any GSM phone, but their 3G networks operate on wholly incompatible frequencies and most phones usually only support one or the other), and you could get pre-pay service with them if your phones are SIM unlocked (I would figure they are). However, the big telcos require a bunch of personal information to sign up for their service. Admittedly, I haven't used T-Mobile in a long time, but I was recently using AT&T's pre-pay and they insist on your full personal details, name, address, all that sort of thing. TracFone doesn't ask for jack unless you use their website. If you buy the phone and minute cards at stores it's completely anonymous.
The anonymity also means TracFones are very easy to sell off when you're done with them, though being so cheap they're generally not going to sell for much unless you've still got a lot minutes left on them. They're basically disposable phones. My friends usually just drop them into a local cell phone recycling box when they're leaving for home. Stores like Best Buy have these, which probably will be one near you if you're visiting major cities.