@palafx - YES YES YES. "A Grammar of Spoken Chinese" is just about the best thing out there, as far as I'm concerned. Y. R. Chao is one of my heroes. Unfortunately, the book seems to be out of print, but anybody who's got access to a university library should be able to find a copy, and secondhand copies are often available for sale (about $80 a copy, the last time I checked) on Amazon. There's also a Chinese translation of the book available and in print, for those who are within the warm embrace of the motherland, and I believe 吕叔湘 - another giant in the field - was involved in the translation or editing of that edition.

For my money, just about anything by John DeFrancis should be required reading. I was fortunate enough to encounter "The Chinese Language: Fact and Fantasy" and "Visible Speech" fairly early on in my study of Chinese, and I am convinced that they saved me a lot of time and effort by steering me away from common misconceptions about the language.

It can also be useful, I think, to deal with different romanizations. Y. R. Chao's Gwoyeu Romatzyh may be a bit of a tall order, but George Kennedy's Yale romanization is designed - unlike Pinyin - to get speakers of American English to produce good-enough approximations of Mandarin sounds, so for people having problems with "x" or things like that -- Yale romanizes that sound as "sy-" -- it can be helpful.