I used 15+GB LTE and another 7GB over wi-fi last month. I work nights so Monday night football is streamed via NFL Mobile now (that's why they gave us the free app right? So we could use it?). Plus I subscribe to several VodCasts that have relatively large file downloads. Love LTE for this. Before the Thunderbolt it would take impossibly long on 3G to get these files so I'd usually opt for the audio-only PodCasts of the same material. I did no tethering at all, this is strictly bandwidth usage on the device.
My relatively vague point is, I'm not an abuser but I most certainly have every intention of using the technology in the way it was promoted by the provider in the first place. It's not like using a lot of bandwidth is going to wipe out spotted owls for cryin' out loud.