BetterExplained
betterexplained.com
betterexplained.com
I looked at a couple of articles and they seem to achieve this pretty well. http://betterexplained.com/articles/understanding-quakes-fas... is a great explanation (previously discussed: http://news.ycombinator.com/item?id=419166) - it omits some detail to better convey the key ideas.
This one's going in my RSS reader.
I'm hoping to crank up the posting frequency, topic suggestions are more than welcome.