I developed the Silvern Moodle theme as part of the Moodle Theme contest.
The theme is based on the concept of "out of the box", because I found that too many Moodle Themes were confined to a square area. I tried to keep the blocks feeling as if they were floating, while the main content is slightly more structured.
More information can be found on my blog post, and the theme can be downloaded from my github account.
Once I've received and incorporated feedback from the contest judging, I'll submit the theme to the repository here on moodle.org.