Also worth bookmarking: The Elements of Style: http://orwell.ru/library/others/style/index.htm
This little book was originally written in 1918, but is still the "gold standard".

And well worth reading, in my opinion, is George Orwell's famous essay "Politics and the English Language"
http://www.protrainco.com/info/essays/politicsandenglishlang.htm
An diatribe from one of the greatest writers in history, what could be better?