There's a gazillion of them. Every time I think "oh I should do that" I Google and find someone already has. Doesn't mean I can't do it better of course. But it begs the question why I don't use any of them. Not one. Perhaps I'm just old fashioned, I write data locally using various tools, events are managed in the family using iCal (everyone has Macs), I don't use de.licio.us, I manage my RSS feeds in Safari (such a luddite). The main sites I read are Slashdot, TechCrunch, The Register and after that it's all news and non-tech sites.
What's wrong with me? How can I expect other people to use something if I don't?