I just wanted to put this out there for those that have not yet signed up for 3G service.
The iPad uses a lot of data. It seems that you could easily use up 100+ mb per day with regular usage. I have been averaging over 100 per day with normal browsing. This is with out streaming video. There are a number of other people out there noting the unusually high cunsumtion rate.
In the interest on science please post your average.