Gmail

You can now say goodbye to unofficial Gmail themes hacks, as Google now officially supports and provides Gmail Themes for a refreshing look to your Google mail account, Google Gmail team unveiled the new themes with 30 brand new themes to spice-up your mail-box with colors, the Gmail theme styling looks quite similar to Orkut Themes, the feature will get rolled out to all users in upcoming days and can be accessed from the Theme Tab in your Gmail settings page.

Google Redesigned is a Mozilla Firefox extension allowing users to change the look and feel of Gmail and Google Calender, Also, known as Better Gmail and Better Gcal the extension achieves the look via custom Cascading StyleSheet(CSS) files which are loaded on the client's browser, The extension simplifies the use of these styles by providing auto-updates, easy management and notifications of changes. You can also download and use the styles individually by going to their respective pages.