Maybe not exactly what you're looking for, but a book that's packed with a lot of useful points beyond the basics:

Martin Durrell, Using German: A guide to contemporary usage.
Cambridge University Press, 1992.
ISBN 0 521 31556 5 ppb.

It may not qualify as a reference grammar in the strict academic/linguistics sense; that is, it's probably not an exhaustive treatment of every possible topic. But it's all rules and examples, no questions or exercises. I continue to find it amazingly helpful and only wish I could commit its contents to memory more reliably.

I'd actually be interested to hear a Muttersprachler's impression of it.

I'm afraid, German native speakers will not have a German grammar at home, but maybe someone can have a look at the bookshelves at some university library.

Off the top of my head (all my grammar books being at home):

Hammer's German Grammar and Usage, Fourth Edition
by Martin Durrell

I actually haven't seen this new edition, but our old copy is well used. It is actually quite advanced, and is really good for understanding the 'subtleties' of the German language.

Ja, "Hammer" wird an englischen Universtitaeten empfohlen. Finde ich persoenlich auch sehr gut, da gut geschrieben und voller Beispiele.

Ich kann waermstens empfehlen: Modern German Grammar - A Practical Guide, Bill Dodd, Christine Eckhardt-Black etc., herausgegeben von Routledge. Wird beschrieben wie folgt: ... an innovative reference guide to German, combining traditional and function-based grammar in a single volume. The grammar is divided into two parts. The shorter section covers traditional grammatical categories .. The larger section is carefully organized around language functions such as communication strategy, expressing likes, dislikes and preferences, comparing objects and actions.

Ich habe dieses Buch bei meinen Privatstudenten mit viel Erfolg verwendet. Hinzu kommt, dass es recht billig ist.

Hammer's Grammar is great. Very detailed, very clear. And the title rhymes.