Username or EmailPassword
I find that I can do all of what you want and more through web-apps (*yes* john gruber's shit-sandwich solution) I presume naïvely that here in the world of HW haxors that wrapping a solution that is 3 or less clicks away (@ google+Automator+Saghoian). Otherwise the iPad is no more a stand alone device than any other other pad or sub-notebook. The issue here unfortunately that we have yet to arrive at that 'city in the sky' where all of your functions are handled by one device - less so one that shares it's screen with a touchpad AND is web enabled - for free (not the $$$ cost but the time cost) and if the solution is to roll a web app that does what you said AND the interface (not just the headers) is free than fish or cut bait.
...This is nonsense.
The solution to creating an all-in-one solution is... a web app?
You seem to think the solution to _any given problem_ is "a web app + something".
It's also not that difficult, and not a very good solution for ...anything. It's a _tolerable_ solution for many things, but it's rarely the _best_.
It's just an outgrowth of various historical events.
It's cumbersome and requires you to write in 3 different languages to get one 'application'. The resulting 'application' is infinitely slower than a native application would be.
You don't even state what this application would actually _do_. I think you're saying it would "connect to the cloud"... Ummmm... Yeah... That's what websites are, really.
A world wherein applications are "network aware" and transparently remote their UIs, remote their storage, remote their CPU cycles. It's a grand vision that has been predicted and attempted many times. All such attempts have failed; the only successful effort has been the under-the-radar "web app" which quietly did these things without raising a fuss or requiring that everyone sign on.
Fast forward to the (near) present and some folks woke up and realized that we have today what Java and NeWS promised but couldn't deliver, we almost have what DCOM was supposed to deliver. It's just wrapped up differently and not at all standard and requires a dozen different languages and formats. So here we are, today, incrementally moving the under-the-radar, it-works-because-it's-open web toward being a real applications platform.
Everything you say is true. Today. But despite the chaos and the mind-numbing effort involved, eventually there will be real useful applications using the browser.