If you are bored of seeing the same Gmail interface over and over, here is a good news, Gmail has rolled out themes for Gmail interface. As usual themes are not yet available for all Gmail users, they will be rolled out in phases. Gmail blog says apart from themes the default look got some minor updates to make it cleaner with color improvements here and there.
They are not enabled for me but Gmail blog has images of the themes, some of these themes are really good. Go to settings in Gmail and look for a themes tab to enjoy these new themes.
Update: I got new themes tab in Gmail, see some of the theme screenshots below.