There are many websites famous at Digg. Most of them get many diggs (some get nearly 5000 and more) and become very famous. They hit the front page of digg. Out of all I discussed about some of the most famous sites.
Cracked

With a caption of America's only humor & Video site since 1958, cracked.com offers funny stuff. Categories include TV, music, Celebrities, Tech, Sex, sports, News and More Funny stuff. It is very popular at digg and almost every article from this site hit the front page of digg and get thousands of diggs.
YouTube

YouTube needs no introduction. Users can upload videos of their interest, home-made or professional, onto this site. Almost every day there will be videos from youtube on the front page of Digg.
Lifehacker

Lifehacker is a blog that features tips, short cuts and downloads that help you get things done more efficiently. This site publishes over 20 tips per day and offers a free download of lifehacker code (productivity of software applications). Most of the blogs from this website get hundreds of diggs.
Ars Techinca

Ars technica (art of technology) is a specialized website in original news and reviews, analysis of technology trends and expert advices on technology. Most of articles from this site get hundreds of diggs and some get thousands.
Live Science

Live Science offers blogs and articles in space, health, environment, technology, history and strange news. Most of the articles and blogs are very popular at digg.
Steam

Steam offers browsing games of all sorts including action, adventurous, racing and sports etc. Many new games are available here and they are quite famous at digg.
PCWorld

PcWorld offers blogs, reviews, articles about all latest tech gadgets including cameras, PCs and mobiles etc. As this site is all related to latest technology, most of the reviews and articles get popular at digg.
Defective By Design

Defective By Design is a broad-based anti-DRM campaign that is targeting Big Media, unhelpful manufacturers and DRM distributors.
Wired

There are many sections in Wired.com including car, culture, entertainment, gadget, gaming, how-to and politics etc. It offers blogs in Gadget lab, Epicenter etc and they are famous at Digg.