Tumblr.com and hopefully muxtape (shameless self promotion). Also if the broadband speed in America increases, DropBox could get huge because it is possibly the best back-up web service out there. A.viary looks pretty promising for graphic artists/web designers
@johnpowell: digg is essentially the web 2.0 version of slashdot. Kevin Rose (digg founder) had asked the guys at slashdot to have a voting system for stories. They declined and digg was created.
Twitter is almost already as big as it can be, I think, and the same is true of Digg. Over the next five years I’d expect to see around 30% maximum growth for the two of them.
In all seriousness, I’m pretty excited for Fluther. Its only a matter of time before it overtakes Yahoo! Answers… and hopefully with a better userbase.
sematic web (some people already call it web3.0) is coming some kind of a meta level beyond the digital social communities, futher a big wave of new mobile device applications (Nokia pushes it) is expected.
I have to think it will involve mobile devices as well. I’m almost certain that in the next couple of years everyone will have Internet and e-mail on their phones.
johnpowell and BirdlegLeft have it right. “Web 3.0” (I’m already shuddering at the jargon) will be all about mobile internet. The release of the iPhone was the first phase.