There's lots of stuff you can do with a PDA phone. Take my HTC Tilt...
Windows mobile 6 PDA phone.
The phone does the following...
* Stores my address book & phone numbers
* Acts as my GPS with TomTom Navigator 6 Also automatically checks traffic and road construction on my route every few minutes and alerts me to reroute if the anticipated delay is too long.
* It automatically checks all of my email accounts every 15 minutes so I can get email when I'm on the road and away from my computer.
* Acts as a broadband internet connection for my laptop when I'm away from home or work.
* Internet Radio. When I go to the gym I stream internet radio over my stereo bluetooth headphones. This allows me to only bring one thing with me. Its my phone and music player. Also since I use Bluetooth I don't have any cords in my way when I exercise. If a call comes in all I do is press one button, and the call comes through the stereo headset.
* Camera. Although I have a very nice digital camera, its nice to have a decent quality 3 megapixel camera on hand for short notice. If I'm at a flea market and I see something I think my mom would want I can take a pic and email it to her. She can check the pics on her computer and tell me yes or no.
* Internet explorer. The phone has internet explorer on it so I can surf sites like ebay and check prices of items I'm thinking about buying.
*Phone. Yeah, it can make phone calls too
I don't have a landline, and haven't in about 8 years. All my calls come to me no matter where I am.
I'm sure I'm forgetting something as well, but that's the bulk of my usage.
-Jay