From my comment in the original thread: (http://news.ycombinator.com/item?id=1353354 http://news.ycombinator.com/item?id=1353354) PlanetMath - http://planetmat

From my comment in the original thread: (http://news.ycombinator.com/item?id=1353354 http://news.ycombinator.com/item?id=1353354) PlanetMath - http://planetmath.org/ http://planetmath.org/ MathWorld - http://mathworld.wolfram.com/ http://mathworld.wolfram.com/ Also, hopefully everyone knows about searchyc by now, but if not, it's a great resource for searching anything technical - http://searchyc.com/ http://searchyc.com/ Edit: how can I forget, one of my favorites: The Portland Pattern Repository's Wiki. HN will love it. It has the same "I could browse this site forever" quality of Wikipedia, but less formal and more conversational. http://c2.com/cgi/wiki?WelcomeVisitors http://c2.com/cgi/wiki?WelcomeVisitors