So do these companies make actual money or they just have revenue?
noodle: skype - got acquired.  users buy servicefacebook - advertising revenueyoutube - got acquired.  primarily advertising revenuedigg - advertising revenue, sells stuff.reddit - got acquired.  displays some ads, but mostly for its parent company.delicious - got acquired.most startups have a plan that consists of one or more of the major 4 plans - sell something, ad revenue, license out your product, cross your fingers and hope to be bought out.a good business relies on one or more of the first 3.  the more of the first 3, the better.