I’m a big fan of del.icio.us <link>. It’s a fantastic way of finding interesting stuff on the interweb. In fact, it’s a fantastic way of getting other people to identify interesting stuff on the interweb for you.
This is my favourite app for extending my network, it’s called network explorer <link>. As well as being useful it’s a nice piece of information design. I also use subscriptions to find links on specific topics and use the RSS’s to feed these and my network into Google Reader. And this page has more del.icio.us apps that I’ve had time to explore let alone use <link>.
I feed my del.icio.us links into my facebook profile too but only because I can. Overall, del.icio.us is powerful, useful and I highly recommend it, unlike facebook, which I don’t.