Would you like to improve your skills at reading and writing?
Then write reviews of the books you read.
There's no better way to tighten your thinking about a novel or an author. What was the book about? Was it any good? Why or why not, specifically? What themes and concepts struck you, and why? What were the book's strengths and weaknesses?
When you read a book with these questions in mind--knowing in advance that you're going to share your thoughts in public--you will read that book on a far more comprehensive level. You'll extract more value out of it.
With non-fiction, a book review not only helps you analyze the book, it helps you hone your own rhetorical skills. Was the author biased in any way? How? Were there gaps in his argument or in his evidence? Did he persuade you, and will he persuade others? Why or why not?
Do this for ten or twenty books and it will transform how you read. You'll no longer be a passive reader, but an active one. You'll take your reading comprehension and your critical thinking skills to a new level. And you will remember everything you read.
Finally, for those readers who are thinking I don't have time to waste writing stupid book reviews, consider this: when you read a book and forget most of it within a few weeks, how much time does that waste?