I'd recently installed the StumbleUpon extension for Mozilla when I came across it being listed as mozdev's Project of the Week for the week of September 8, 2003. StumbleUpon is not just a Mozilla thing - its homepage has toolbars for IE and Netscape 7 too.
What it does is to allow you to 'stumble upon' sites that are recommended by peers with interests similar to your own. You can recommend (as well as disapprove of) sites yourself too. Pretty neat idea if it doesn't get abused by webmasters.
And before you ask, yes, I was bored - I was "running out" of sites to visit.
I did manage to uncover some interesting sites in my stumbles. Like Acronym Server (decodes acronyms - great stuff!), Make A Shorter Link, a feisty new Linux distro, and even this essay on "How to Write Unmaintainable Code"!