stackoverflow.com looks great and is really needed. Half the time you search for some error message a server spits back at you when you did something wrong you get one of these expert sites which wants you to pay to get the answer. The other half of the time you get a mailinglist link and have to crawl though the threads to find out if the question was answered or just flamed.

Other than the funny captch I got when trying to log into it with my flickr.com account it looks really good.