There are no other ways ways of including new themes to gmail but this wonderful post on dynamic Gmail themes which change pictures and looks with time of the day or hourly have a great thing for improving appearance..
http://sameerkhansblog.blogspot.com/2009/01/gmail-themes-dynamic-pictures-Google.html
There is no orange clock in Gmail. It might be a theme which is present in the Gmail. You can make it to default theme.
Unfortunately you cannot change your theme on Gmail on ipad.
Black is one of the theme of Gmail inbuilt. You can change your Gmail to black anytime you want. In the settings, there is themes where you can select it.
You cannot add your logo to Gmail account. You can personalize by adding your theme. Adding icon or logo to Gmail is not possible.
The themes are included inside the Gmail website. They are for making the webpage more interesting. A person can select the theme which interests him/her.
Gmail has various themes present in it. The theme helps to build the person his account as he wants to. The themes are present in the settings tab.
You can select a theme from white and black and can customize. You can add your own background. It can be from a URL, picassa or anywhere in your drives.
You can add photos to your Gmail profile background easily. The background can be changed in the themes bar. You can select the theme that interests you.
Unfortunately, the ability to change the theme of Google's search engine on '.co.uk' is no longer available, so you will not be able to save the theme as a desktop wallpaper.
Go to settings, themes, and apply one. Settings is in the upper right corner.
You cannot create custom theme for anything. However you could change some of the properties. Like you could set a custom background image.
In the top-right of your gmail account you can see a few options. 1. Out of that, click settings. 2. In that get under themes tab. 3. Select a theme. 4. Now you're done. :)