Unfortunately, this was the first link on Google.
Ray Charles would know that breasts don't look like that.
Just do not go there.
However I found a great anatomy book. Figure Drawing for All It's Worth by Andrew Loomis. It was mentioned in one of the Sequential Tart's online columns. There's 197 pages of drawings, sketches, diagrams and every conceivable pose. (Well, maybe not a pose of Justin Timberlake reaching over to tear off Janet Jackson's bustier) And best of all, it's available free!
It's a big PDF file, though.
(There's also a copy here at www.fineart.sk as normal graphic files)
I also found what appears to be a good tutorial. In general, the online tutorials focus on the same things (well, because people keep making the same mistakes), but some little details one might overlook is hit upon by another.
OK, I'm going to end my obsession with this for a while.