Besides that hack there’s a whole lot more on gMail and rest of the Google eco-system (Blogger, YouTube, etc.)
One of the new style O’Rielly Hack books, this one looks at how to use Google’s applications through a series of short examples (aka hacks) covering, not just the office applications, but many other applications under the Google banner. For web designers, there’s a lot of material here too on how to integrate Google’s services into your own website.