Oh grammar geeks of SDMB, would you help me locate a good book or website?
The Transitive Vampire by Karen Elizabeth Gordon. Not only good, but fun to read.
And avoid Lynn Truss’s Eats, Shoots & Leaves – she knows nothing about grammer; it’s filled with errors.
The Elements of Style, by William Strunk Jr.
Does she know how to spell it? 
(Sorry, couldn’t resist.)
Truss’ book is meant to be humorous more than primer in nature. I sure as hell wouldn’t bring it with me as a reference for my work.
There are a lot of fair grammar sites out there and a lot of really poor ones. Accordingly, I tend to stay away from recommending any one over advising based on specific questions.
A standard reference book, but for grammar, I’d recommend The Elements of Grammar. Note that the two together are cheap.
Since I’m a journalism major, this also has AP style thrown in the mix:
You can actually find the 1918 edition of Elements of Style online, at Bartleby.
For American usage in book form, i highly recommend Garner’s Modern American Usage.
You might take a look at www.grammarboard.com. Their forums are fun, and full of good advice.
Uck, uck, uck. There
Uck, uck, uck. There’s some style advice in it that’s useful - if you’re a good enough writer to know not to take their advice too seriously - but a lot of other stuff that’s sheer nonsense. Strunk was a bit of an old crank, and unless you’re prepared to ignore half the book - and if so, you don’t have much need for it - you’ll discover the incredibly poor advice to, for instance, exclusively use “persons” and not “people” as the plural of “person”.
It’s interesting as a cultural touchstone, as it’s such a widely-known book, but it’s a terrible place to go to get actual advice on writing.