Oxford University Press
Eastwood's "Oxford Guide to English Grammar" takes a more functional approach to grammar than some books. It is a good book to use in conjunction with some others, such as Practical English Usage: Hardcover.
The chapters that Eastwood breaks his book into are as follows:
1. Sentence and Text
2. Verb Forms
3. Infinitive, Gerund and Participles
4. The Noun Phrase
5. Adjectives, Adverbs and Prepositions
6. Main clauses and Sub-clauses
7. Word Forms
Each section is fairly extensive and gives a good deal of information for most teaching purposes in the language classroom. They have a huge range of topics within each including articles, quantifiers, adverbial clauses, conditional clauses and the list goes on and on. The examples given are well-chosen, though these sub-sections seem to lack some of the extensiveness that other books suffer from. However, I think it is more than enough for most practical purposes.