In August of 2013 I've been seeing ads on tv from Virgin Mobile for non-contracted, I-Phone 5, LTE, unlimited text and data. I don't know anything about who they buy service from (Sprint I imagine) but for some people this may be worth looking into if you can afford the upfront equipment purchase. But iphones are special for those who enjoy being able to get all the latest and greatest apps.
http://www.virginmobileusa.com/
But I suspect the data throughput is probably severely monitored and regulated and systematically throttled back for heavy data users. Just though I'd mention this.