As you may know, I'm a huge fan of Doug Green's. There is no garden writer that I know of who has more knowledge about growing stuff. I also love his no nonsense, clear (and sometimes delightfully curmudgeonly) approach to gardening of all kinds. Doug Green's Garden is one of my go to websites for information.
I just got his newsletter that announced that one of his electronic books for Kindle is on sale at Amazon for $3.99: