Theme Creator allows you to create themes for your T68i. The process is very easy with the clean and straight forward interface. You pick the colors and images you want and preview them in sample screens until you are satisfied with your creation.
The program also allows you to view and extract files and images from existing themes. It also supports two plugins, IrfanView (which can be downloaded for free and GIF color palette optimizer (which is preinstalled).
In the screenshot above you can see the PC911 theme I created. If you want to try this theme for your phone, you can download the theme here: dloads/pc911_phone_theme.zip
Download the file to your hard drive, extract the file PC911.thm, then use SendFile for example to transfer the file to the phone.