I like plain template with no or minimal graphics as my blogs are generally for the purpose of providing information. However, it can become quite dull. Hence I though of adding some color. The easiest is to add a color background to the Header. Color background does not increase the download time as would a graphic background.
Next is to add a horizontal menu bar with a slightly different background color from that for the blog title. I am testing that at Lincoln Chew blog. Please do give feedback by commenting and tell us what you think of that little bit of customization.