Pretty Good Gmail
Following the footsteps of Google’s personalized homepage, Gmail added themes. Once the new option is enabled in your account (as usually, Gmail’s new features are slowly rolled out), you’ll find a tab named “Themes” in the settings page and you’ll be able to choose from 30 themes. “We wanted to go beyond simple color customization, so out of the 30 odd themes we’re launching today, there’s a shiny theme with chrome styling, another one that turns your inbox into a retro notepad, nature themes that change scenery over time, weather driven themes that can rain on your mailbox, and fun characters to keep you in good company,” mentions Gmail’s blog.
There’s even an old school ascii theme (Terminal) which was the result of a bet between two engineers — it’s not exactly practical, but it’s great for testing out your geek cred. We’ve also done a minor facelift to Gmail’s default look to make it crisper and cleaner.
To customize your inbox, go to the Themes tab under Settings.
Unlike other webmail services, Gmail has never provided too many customization options and users had to rely on themes created for third-party extensions like Stylish, which usually slowed down Gmail and weren’t resilient to code changes.
http://gmailblog.blogspot.com/2008/11/spice-up-your-inbox-with-colors-and.html