Well with LTE I have noticed I've been using a TON of data. In 2 days I've used 821MB. That's purely browsing, no downloading (except a few small apps), no streaming of movies or anything like that.. It could be that it's new and I want to try everything but still I'm finding it a bit weird...
Also, I'm sure there is a cydia tweak that allows you to turn off images in safari. I used it when I only had dial up at home.
...? im assuming this is all related to iphone 4 and up. i can browse through 20-40 pages on at&t's 3G on a 3GS and only use about 10-20 mb... with onavo, i use even less