John Piper doesn't need me to introduce him, but I don't know if all of my readers read the Desiring God Blog.
It's actually a group-blog with multiple authors, some from within the DG ministry, and many from outside friends.
Piper tends to write something about weekly, and they post his sermons, too, but there is normally something new from others at least once per day. (One of my favorites is Jon Bloom.)
The content is doctrinaly meaty and yet liveably practical. I am normally encouraged or challenged (or both) by at least one post per week.
For example, last week, my former professor of preaching Mike Bullmore posted a meditation on training up the next generation.
In it, he opens up about his own temptations to just finish well on his own and in his own generation but not to think beyond his generation, and then he ends with some short but to-the-point applications:
This is the kind of thing to expect on the DG blog. I highly recommend it.
Invest in the Next Gospel Generation