WordPress – Multiple Columns with WP Easy Columns
WP Easy Columns allows you to convert any page or post, in any theme, to a magazine style layout in just a few clicks. With Easy Columns, you can insert unlimited number of columns and at least fifteen combinations of 1/4, 1/2, 3/4, 1/3 and 2/3 width columns.
WP Easy Columns in the WordPress plugins repository
Plugin instructions & demo: WP Easy Columns for WordPress