There's a Firefox extension called Better GMail which Gina Trapani from Lifehacker has put together. It's a compilation of Greasemonkey scripts that enhance various aspects of the service, from its looks to its functionality. Google has a history of taking the best bits of the extension and adding them officially to GMail, and now they've added the popular 'themes' functionality. The themes look damn good - there's giraffes, ninjas, the themes can change over time, or with the weather, and there's even an old-skool ASCII theme. The themes will be rolling out across GMail over the next few days. They're not enabled on my account yet, sadly. Have they shown up on yours? Which is your favourite? Let us know in the comments.