I found this hack is very useful particularly when I was designing my home/ index page display. I wanted my homepage displays news in two, three or four columns. And this hack perfectly fits into this need.
Please go to the source: <http://www.transformationpowertools.com/wordpress/multi-column-wordpress-template>
What you need is just simple php code with simple one line .css style:
There is another similar, but more complex example here: “6 Ways to Display WordPress Post Content in Multiple Columns”
Just have a look and see which one suits you best.