Someone asked me the other day if I had to winnow all my devices - and lord knows, I own many - down to one, which one would it be? My answer took a nanosecond; no question about it, my iPhone. It does absolutely everything I need and it's fundamentally a computer in a pocket. It's not even close, but if phones didn't count, it would be a very close contest between my iPad and McBook Air and I might actually go with the iPad. It's a pretty practical device too, in the spirit of the iPhone, but now that I have a Kindle Fire in the house, I really wish the iPad came in the same size. I suspect we might actually see that in the coming weeks.
In the same spirit, if I had to winnow all of my websites down to one, it would be twitter. Twitter is invaluable to me and is my conduit to the news of the day and more. Facebook would probably be my second choice though I am quickly growing tired of it. It seems like my entire newsfeed is nothing more than a large group of moms bitching about hard they have it. I recognize that that statement probably won't garner me any friends but alas, it's true. And respect to those moms - I know they don't have it easy - but sheesh.
If I could create my dream product, it would probably be a nuclear-fuled super battery of some sort; I am tired of having to charge my devices - most particularly my iPhone - every hour.
Back to the device - curious as to your pick, iPhone notwithstanding.