A favourite of mine is Stephen King Page, especially the list of crossovers in King's work. Very ambitious.

Horrorking.com's Stephen King Page seems set on covering all things King, and does a good job of it. Plenty info on stories and films, news, pictures, discussions, interviews and lots of links.

Stephen King News has a humble, low-key layout, focusing on content (news and stuff) and doing it well.

The imaginatively titled Stephen King Web Site is a nice source for facts and news.

Not to be confused with Stephen King WebSite which mostly consists of links and news.

Stephen King by TJ has thoughts on mainly the Bachman books and The Dark Tower series.

There's an official site as well, of course, with news and a brief biography.

And don't forget the King newsgroup, alt.books.stephen-king.