My smartphone has actually saved me from getting toll violations. I take toll roads between my home and my university since I'd rather pay a few more bucks to avoid the eternal torment that is I-95, and in order to facilitate that, I have a Sunpass (Florida's RFID toll paying device). But the RFID chip isn't enough - you also have to list the license plates of the vehicles you've authorized to use the device in your account settings. I was stopped for lunch before hitting the toll road, but too far away from my apartment to justify going back (unless I'd been without a smartphone, of course), when I realized that I had forgotten to register my new 17S license plate with my Sunpass. I just whipped out my phone, logged on to their mobile site, and voila. Crisis averted.
Also, anyone remember #alloyofline? That was brought to you by smartphones. That wouldn't have been possible via SMS Twitter, since you can only link one phone to a Twitter account that way and all five of the admins (at the time) were tweeting like crazy people from the main 17S account.
Anyways, I have a Droid 3, and I adore it. Best phone I've ever had, by far.