Slashdot is definitely a niche thing. It even identifies itself as such. One of the website's taglines is 'News for Nerds'. This interest group is a pretty big niche, but it's still a niche.
Also, even among the techno-centric set, there's now plenty of alternatives to Slashdot. It doesn't have the dominance that it did a few years ago. Things change.
That said, even if you haven't heard of Slashdot, you might be familiar with some of its sister sites. The same people own and operate Thinkgeek and Sourceforge.
@Acyl
VIRTUE
Blue: Realpolitik, Leading Lady, Glass Lass, Superball, Alec Kazam
Red: Battery Acid, Obsolete, Bugfix
@True Metal
Co-leader of Callous Crew SG. Based on Union server.