I'd like to be able to find out my internet usage for a given time period, in number of bytes transferred (in and out). I'm about to take a road trip and I'll be surfing on my iBook via a USB connection to my Sprint phone. Since this is an unsupported feature, I don't want to call attention to myself by using enormous gobs of bandwidth. (Plus, my kids will be using this too.) Is there an application that can give me this information?