After its search and advertising core businesses, one of Google's hottest products is its Gmail service.  One of the most widely used free email services on the internet; Google is constantly at work improving the service.  Typically upgrades target greater functionality, such as a recent upgrade that added voice and video chat to the Gmail portfolio.

However, Google has rolled out a new set of changes that are just pure fun.  Google has followed in the likes of Microsoft and Apple in realizing that customers like nice looking UIs and is rolling out 30 new themes for your Gmail inbox that will help it stay "more in tune with your personality".

Google search guru Marissa Mayer brought an early version of such themes to the table with the snazzy iGoogle themes in the summer of 2008.  These artist-developed themes were much lauded for bringing an artsy side to Google's services and look, while keeping the UI very usable.

Currently Google is in the process of rolling out its new themes.  When you receive them, simply navigate to your "Themes" tab and check out the new features such as the Graffiti theme.  All users should receive the themes over the next few days.

Google guru Annie Chen describes the update stating:

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. 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.

Yahoo currently has about 30 percent email client market share compared to Google's five percent.