In this ZDNet Australia article about MySQL, it says:
Much of the very busy Yahoo! Finance portal uses MySQL as a back-end database.
I find that statement quite remarkable because it's simply not true.
Yes, Yahoo! Finance uses MySQL as a back-end database. But much of goes a bit far. Most of the Y! Finance data is served from memory, not from MySQL. Yes, there are parts that use MySQL quite a bit, but they're not in the majority.