The keyboard and the push email.
I once heard something about a 02 sim from the UK that is like 5 pounds per month and gives a couple hundred MB of international roaming data.
I have the SGS3, but I still use my BB for business emails (I type faster on keyboard).
O2 have a 'bolt-on' for blackberry that costs £5/month for 500mb data. The thing is, it used to work internationally, and I know many people in the US that would use it.
Recently, they changed things, and now one could only use the 500mb in the UK. They have a roaming bolt-on which costs £5, but you only get 10mb for the month.