That is a good point. You can keep flikr private if you want. I can get lost in flikr doing searches on tags and sets and groups. I have found a few very talented people who's flikr pages I have saved and check into to see what they are doing now and then. Never posted an image myself though.
It's the biggest stock photo agency in the world....
Just kidding. But it's true in a way, there is a lot of photos there that you can use according to various licenses. I have been occasionally using them for work, when we needed a quick snap of something to illustrate a web page.
Using film since before it was hip.
"One of the most singular characters of the hyposulphites, is the property their solutions possess of dissolving muriate of silver and retaining it in considerable quantity in permanent solution" — Sir John Frederick William Herschel, "On the Hyposulphurous Acid and its Compounds." The Edinburgh Philosophical Journal, Vol. 1 (8 Jan. 1819): 8-29. p. 11
Think of Flickr like a room full of 1000 people with cameras. There's no official directory of the "best" photographers, so you just start with the people "near" you (randomly). If you like any of their photos, then ask them who they like, and continue on that way. If you don't see anything in someone's photos, just move on.
I rarely browse Flickr using a web browser, but instead subscribe to particular "feeds" of photos from individuals or groups, using an RSS newsreader (in my case, NetNewsWire on the Mac). That way I keep up with the current photos from the people whose work I enjoy the most.
Personally, I find Flickr to have an incredible depth of quality, often far better than edited pro/fine-art sites. There are really some amazing photogs out there, sometimes folks who are not at all professional.
Here are links to several photographers (and one group) that I especially enjoy:
John has the key point in my mind. Start finding photos that you find interesting. Then add the owner as a contact. See what he likes and if you like some of them, add them too. Slowly, your web of contacts grows. And every time you log in (or monitor with an RSS reader), you get updated on your contacts' new photos. Can be quite fun.