Well.. as I suggested, I'm referencing the info I get from AT&T and not the phone. This makes more sense to me. After all, that's what counts here.
My usage is 174MB with 10 days left in my cycle. I check email often, but manually;push and fetch are off. I use Mobile Safari just about every day. Say, 10-20 minutes per day, on average. Send a few photo attachments per week. The occasional YouTube video or other streaming; not much. Checking sports scores, account balances via apps, etc. I'm online as often as needed and without caution of the data I use.
That's about all I can think of. I guess I'm the average user.
Hope that helps.