How many Data Plans does one family need?

Once upon a time, mobile device with internet data was a luxury reserved only for the upwardly mobile professionals.  Internet on mobile was paid for by the KB and it was slow.  Today, its not unusual to see young professionals rocking out a smartphone with unlimited data plan.  In some cases, an individual might end up with two phones connected to internet data (business issued BlackBerry and personal iPhone).  Housewives now rock smartphones with data plans as well as children as young as 7 years old.

This is pretty insane given that the network carriers are selling you the same internet to everybody without really the need to incur incremental expense.  It is in their best interest to re-package their wireless data network and sell them to you as many times as possible.  Below  is an example of what a typical family might encounter:

1. Dad (at least one smartphone with data, possibly two if work issues a blackberry)
2. Mom (at least one smartphone with data, possibly two if work issues a blackberry)
3. Either spouse might have a work-issued Wireless Modem or Mobile Hotspot like MiFi)
4. A 3G iPad or Netbook with integrated wireless package/card
5. In-car mobile/data account like GM's OnStar, Mercedes mbrace or BMW's Assist
6. Children in grade school probably has a smartphone with data package and unlimited text plan

At one point, we had 5 devices that are connected to mobile internet... its down to 3 today.  Crazy!