Following on from a discussion on Handakte WebLAWg on style, here are some style guides:
For the USA:
The Chicago Manual of Style
The Chicago Style Manual website also has FAQs, for example on how to write Internet and Web terms, although I prefer email to e-mail
For the UK:
The Oxford Style Manual (this consists of the Oxford Guide to Style and The Oxford Dictionary for Writers and Editors in one volume, which may be a bit unwieldy – I haven’t seen it).
Many newspapers have online style guides:
The Guardian
The Times (aka The London Times!)
Here is part of the Times one: The Times on courts of law.
The EU has an online English style guide.
BBC News Style Guide
(click on Open Guide 1)
Sweet & Maxwell (British legal publisher) House Style Guide.
There are some links about style in the original Joi Ito entry of January 18th. Note that the Chicago Manual of Style is more about formal requirements, whereas Strunk and White’s The Elements of Style (mentioned in a comment) is about writing style.
Then there is writing in a way that makes sense on the Web. Jakob Nielsen is a good source there.
Speaking from a U.S. perspective: in some respects more important — or, at least, more useful — than the CMS is the AP Stylebook, which goes beyond just journalism (despite its self-imposed nickname).
@scribe: Thanks, that sounds good. I actually stopped short of books like this (except for Strunk & White) because I thought, maybe I should do another entry. I have another book on how to write, Joseph M. Williams on Style, and when I was looking for it I found Harold Evans on journalism (British) and Keith Waterhouse, to say nothing of some books on legal style. Those are the more interesting books, although I don’t open them so often.