What all can a cell phone replace functionally? Besides being a phone, I can take pictures, shoot video, record audio, keep time, generate a map (no gps for my phone yet, though I see it coming), check email, browse the internet, use it as a daytimer, use it as a low light flashlight, an alarm clock, listen to music, watch movies, and I am sure there's plenty more. I do still carry a flashlight and a watch on my person so there is some redundancy, but it is amazing how much they've crammed into the little platform.