JSTOR :P

More seriously, I only read them infrequently but I quite often see people recommend the Smithsonian and BBC History magazine websites here as coming out with interesting, accurate articles for a general audience.

• The Junto, a blog on early America written by academics, with very readable articles.

• Age of Revolutions, on world revolutions. There's an emphasis on the American, French, and Haitian revolutions but there are articles on other ones too.

• The online Holocaust encyclopedia run by the U.S. Holocaust Museum, which has articles on the Holocaust and also the interwar years and WWII in Europe.

• The International Encyclopedia of the First World War about WWI and the different events and historical phenomena associated with it. It has a very broad scope and is not confined to Europe and the U.S. It also contains a lot of social, cultural, and political history instead of just military history.

• Liberty, Equality, Fraternity, an online exhibit about the French Revolution. It's very well written, and contains essays, images, and primary sources. One of the editors is Lynn Hunt, an eminent historian of revolutionary France.

• Revolution and the Fall of the Wall, an online exhibit about opposition to communism in East Germany, the fall of the Berlin Wall, and German reunification. Has a lot of great images.

• Seventeen Moments in Soviet History, about the history of the U.S.S.R. Contains essays and primary sources. I haven't read much of this one yet but what I have seen is good.