I have a love/hate relationship with my smartphone, but I'm still amazed at some of the things I can do with it. Adding to your list:
When my car's GPS took me miles down a road that was washed out on a trip hundreds of miles from my home, Google Navigation on my smartphone suggested a different route that got me safely to my destination.
It's a flexible and reliable alarm and kitchen timer.
I can read novels comfortably in bed on my smartphone (none of my several laptops are very ergonomic for this purpose).
I can map my bike rides and get stats on min/max/average speed, elevation, etc. (all the while using it as a music player).
It lets me easily maintain multiple shopping lists.
I can tune my guitar with it.
It functions as a real flashlight (my phone has a very bright LED).
My smartphone is no replacement for a computer, but it's better at these tasks than any computer I own.
> I can read novels comfortably in bed on my smartphone
Really? I tried with an iPod Touch and an iPad, and really hated both. Then I bought a Kindle and found it extraordinary. The Kindle is the best device I've ever owned.
I bought the Kindle when it first out and loved it but never carried it with me, and found it difficult to read at night - so as soon as reader version came out for my Android, I used that and never looked back.
Reading in bed with a smartphone is great because the light does not bother my partner, and after two minutes of my falling asleep, the phone switches off its screen as well. Any bed lamp I use keeps me awake rather than allowing me to fall asleep.
(I know I am the exception as I have been reading on Palm Pilot screens since the late 90s - it was the only way to make sure I could get enough reading time in medical school.)
Not only that. To the GP: I read also on my phone (Nexus one) but I feel the backlight is not very gentle for my eyes, even when using FBreader in night mode. Also, characters are too small. To me, a (real B&W e-ink) Kindle is better, or a paper book.
Actually, if you get a phone with the AMOLED screens, you can read in direct sunlight. I have a Nexus S, and I do that every single day. I take it out of my pocket the moment I step outside, the screen automatically jumps to full brightness, and I have no problems at all using the phone to read emails, set up GPS while I'm walking to my car, or compose text messages. I can even do this with my sunglasses on.
I have both an eInk Sony reader and a B&N NookColor, and both are pretty good for reading. I prefer the eInk for casual reading, but the Nook is great for PDFs and papers, and reading in bed without light :)
Oddly, with the conceit of an offline GPS app (map data in the phone) every item you listed would work without a mobile data connection.
The killer network-enabled app is still on the drawing-board. (I don't feel like being able to instagram a photo and have your friends "like" a black-n-white photo of your dinner WHILE YOU ARE STILL EATING IT! is it).
Why not using your phone navigation then? Here in China, without turn-by-turn GPS, I would be lost in nowhere, and the Chinese things they sell as GPS don't count.
> My smartphone is no replacement for a computer
Mine is, in many cases. Before, I was in the habit of turning on my laptop to check some pages or feeds after dinner, now I do this confortably installed in the sofa, on my phone.
I just miss, obviously, the content production abilities of a computer. Hope they'll find quickly a way to input text conveniently in a phone-sized thing. (I won't bet on the voice for that, maybe just a good hand writting detector could work as well)
Text input in horizontal mode is pretty comfortable, IMO, but then the screen you are inputting into usually isnt visible. I'd like to see a phone with a popup screen for horizontal mode. :P
edit: oh yeah, they make slide out keyboards for this exact reason. totally forgot about those.
When my car's GPS took me miles down a road that was washed out on a trip hundreds of miles from my home, Google Navigation on my smartphone suggested a different route that got me safely to my destination.
It's a flexible and reliable alarm and kitchen timer.
I can read novels comfortably in bed on my smartphone (none of my several laptops are very ergonomic for this purpose).
I can map my bike rides and get stats on min/max/average speed, elevation, etc. (all the while using it as a music player).
It lets me easily maintain multiple shopping lists.
I can tune my guitar with it.
It functions as a real flashlight (my phone has a very bright LED).
My smartphone is no replacement for a computer, but it's better at these tasks than any computer I own.