digg -- Ranked popular links, news, videos, images, sharing,... categorized and customized...

dmoz -- "open directory project" -- Largest website compendium on the web. Categorized and edited by humans.

craigslist -- Popular no-frills site for buying, selling, renting, personals and just about anything else you can think of...

technorati -- "search the blogosphere" -- Technology, business, boating, entertainment, lifestyles, politics, sports...

Bloglines -- Free service that serves news, blogs, weather -- customized for your interests. Also available for mobile devices.

reddit -- Links to blogs on every topic... Submit, share, bookmark... top links, random... mobile app available.

StumbleUpon -- Discover websites on all topics visually through thumbnails... Submissions by members, toolbar...

bing -- Visual Search -- Microsoft's search engine that presents images of categories to choose from.

Outpost-Earth -- Version 2 of site designed to drive traffic and exposure for bloggers...

Zibb -- "The Global business search engine." -- News, categories by industry...

del.icio.us -- "social bookmarking" -- User generated lists...

WebRing -- One of the original ways to discover websites of similar topics and interest. Categories, blog...