At last count, OnlineStylebooks.com included 86 online style guides, covering a variety of fields and organizations that range from Adobe to Yahoo with NASA in between. You can follow the links in the list of stylebooks to see individual guides, or you can search all of the stylebooks at once.The alphabetical list of style manuals notes that the content of three of them is available by subscription only. Those sites are published by three of the style manuals I consult most often: the Associated Press Stylebook, Chicago Manual of Style, and Gregg Reference Guide. Garner's Modern American Usage is also one of my most-checked manuals, but it doesn't have an online version.
I've subscribed to the online versions of AP, Chicago and Gregg, though I now subscribe to only the AP guide. Of course, all three (and Garner's excellent manual) are within easy reach on my desk.
I also frequently check one other site listed at OnlineStylebooks.com, my own: Garbl's Editorial Style Manual. That was a pleasant surprise!
Stahl's article is featured today, Feb. 1, in my online daily paper, Garbl's Style Write Choices, available at the Editorial Style tab above and by free email subscription.