Modern Tibetan
"Manual of Standard Tibetan" by Tournadre and Dorje is solid. It's what we used in my first-year Tibetan course and the standard, I believe, for learners of Modern Tibetan. Lots of good grammar description, including appendices on differences between registers of Tibetan and dialects of Tibetan. Its descriptions of grammar in the lessons themselves are less linguisticky than the ones in the appendix but they are all usable, though watch out for its non-standard transcription scheme.


Basque
Standard Basque: A Progressive Grammar by de Rijk is a wonderful thing: it's a reference grammar, with example sentences and vocabulary. It presents the easier grammatical structures (rules of the definite and indefinite articles and what not) first, and then moves later onto the more challenging Basque verbs, with meaty grammatical descriptions for everything.


That's all I've got for now - I'll probably think of some later.