Informality rocks!
In my current day job, there are some people (who shall remain nameless) that seem to want the language of our site to sound very 'corporate'. You know what I mean: that language that sounds as if it were coming straight from a fleet of lawyers, who seem to have very carefully selected each word in some attempt to sound classy. Not that sounding classy is bad. It has its time and place. But come on! Show your wit and sense of humor when you're making a website! It's not a matter of making the entire site like one joke attempt after another, but spruce up the language a bit and make it fun. Don't be serious all the time.
Here are some screenshots of some sites that I use, that I want to use as some sort of guideline for future sites that I work on, especially those moments when the user has to wait around for something.
When you add a new feed to FeedBurner, it takes a while for their servers to set up your feed. In the meantime, instead of saying something like "Your feed is not ready - Come back later", it lets you know that they're playing with the bubble wrap while in the process of getting set up. Whoever has had to set up something that came in a few layers of bubble wrap knows that this is exactly what we do.
When GitHub renames one of your repositories, we don't simply get some renaming action going on - We get hardcore renaming action! I actually laughed out loud the first time I saw this.
I'm a huge fan of the Pragmatic Programmers and most of their products. In my eyes, the fact that they employ gerbils to do their work makes them even cooler! Well, not cooler, but I do chuckle whenever I envision some gerbils pushing buttons to regenerate a PDF.