One tool I use a long time ago is CSS mutli-column generator by Jerome Debray. This tools helps me to make a correct CSS for create <li> in sereral columns. Simple example:

• Column 1 - Row 1
• Column 1 - Row 2
• Column 2 - Row 1
• Column 2 - Row 2

CSS used:

-moz-column-count:2;
-webkit-column-count:2;
-o-column-count ...