The Cambridge Grammar of the English Language sets out the language in piercing detail, but I often find it overwhelming and need to step back and bring together what I've read in a way that displays the basic relationships minus overmany particulars. Recently, my attention has been on subordinate clauses. Five years ago I would have said I had a good understanding of subordinate clauses, but how wrong I was. The more I delved into it, the more I found and the more lost I felt.
In the following taxonomy/tree diagram/organizational chart, or what-have-you, I've attempted to illustrate the relationships between all these various subordinate clauses. As time allows I'll add example sentences to illustrate each.
PS, If somebody can conjure an elegant way to allow telescoping of the various daughter levels (click-to-expand kind of thing) along with links to example sentences, please let me know.