Creating Columns in Articles

I was going to write a blog about this subject, but I found someone else blog that already does it. Rather than be a jerk and steal his (or her) content, I'll just link to it.

http://texblog.wordpress.com/2007/08/11/creating-two-columns-in-article-report-or-book/

The only thing I would add is that, for anybody that uses the \textwidth variable, it still refers to the width of the page, and not the width of the column, so use \columnwidth instead.