One of the new MVNOs is Solavei."Solavei is a pre-paid wireless service that operates on T-Mobile’s network. Anyone can sign up without a contract or any commitments. The monthly fee is $49 which will get you unlimited talk, text, and 4 GB of data before you get throttled. It works pretty much like any other pre-paid service, with one major exception," writes this article. It has an MLM sales engine - referrals with a punch, I guess. Solavei also encourages folks to bring their own T-Mobile phone - you get a free SIM to make it work with Solavei.
The other data MVNO is an old ISP fan: "NetZero Wireless, Inc., a subsidiary of United Online, today announced the launch of the NetZero 4G Data Share program. Through this new program, any of Facebook's millions of U.S. members can sign up at www.netzero.net/datashare and receive one free gigabyte of wireless data per month to give away to their friends via Facebook. All of the free wireless data that is given away can be claimed by the Facebook member's friends through the NetZero 4G Data Share app and can be used by NetZero 4G Mobile Broadband subscribers with any data plan, including the 200MB/month free plan." A little bit of social sharing built in.