The New York Times has a weekly column called After Deadline, “Notes from the newsroom on grammar, usage and style.” In this column, Philip B. Corbett, the associate managing editor for standards (who is also in charge of The Times’s style manual), points out grammar and style errors from recent editions of the newspaper.
I learn a lot from this column. While some of the points are specific to The NY Times style guide, many are related to general usage and grammar issues. The examples given are representative of the complexity of everyday usage.
It’s the cart-before-the-horse problem: usually the grammar and usage examples that are given to illustrate a particular issue are simplified to make the issue clear and understandable. The problem is that normal usage is more complex, so it is illuminating to see grammatical analysis of complex sentences.
Further to this, Brian Garner’s Modern American Usage is an excellent reference that uses examples from print media to illustrate grammatical rules. It’s back-of-the-toilet interesting.