A simple way to adjust or tweak a theme to your liking can be as simple as a few lines of css code in styles.css.  I made a couple very minor changes to achieve the affect of a new background color, content on the right when it was always on the left, and a font color change to go along with the background better.  This is what it looked like:

/* I replace the Standard body formatting:
body {
    background-color: #F1F1F1;
    color: #444444;
    font-family: Verdana;
    font-size: 11px;
    margin: 0 auto;
    width: 980px;
    position: relative;
}*/

/* With the following: */
body {
    background-color: #6699FF;
    color: #444444;
    font-family: Verdana;
    font-size: 11px;
    margin: 0 auto;
    width: 980px;
    position: relative;
}

/* I replaced these lines:
#content {
    float: left;
    width: 70%;
}

#sidepanel {
    float: right;
    width: 28%;
}

    With this...   */

#content {
    float: right;
    width: 70%;
}

#sidepanel {
    float: left;
    width: 28%;
}

/* I replaced these lines:
#header span {  font-weight: normal;   letter-spacing: 4px;

color: silver; margin: 0px; }

#header a { text-decoration: none;  color: white;  }

    With this...*/

#header span {  font-weight: normal;  letter-spacing: 4px;

color: #0000CC;  margin: 0px; }

#header a { text-decoration: none; color: #0000CC; }

Then there was the slight issue with the Date Time format on the Blog post.  This is an example of a minor inconvenience and a quick and dirty solution.  I'll describe an alternative approach later.

Notice the formatting for June 29, 2008.  This date can probably be localized, but today it's hard coded in PostView.aspx.

Note: I changed

    <%=Post.DateCreated.ToString("d. MMMM yyyy HH:mm") %>

To...

    <%=Post.DateCreated.ToString("dddd, MMMM dd, yyyy hh:mm tt") %>

To get the following results:

Yeah, I know this wasn't earth shattering.  But the premise is simple.  If there's a theme you want to use, except for a couple small items, change them.  The next step from here is to create a BlogEngine.NET theme for version 1.4.5, using an open source.  The Widget Zone needs a little tweaking on some of the older 1.2 and 1.3 themes, but we've already done that once (It's just about time for a new theme and BlogEngine.NET 1.4).  I hope everyone tries that once so we can have a few more themes right away.

Here's the new theme.  I'll call it nonStandard since I'm not a marketing guy: nonStandard.zip (6.28 kb) .  Enjoy!!!