As a prototype, you can start with the following HTML:
<ul class="two-col-special">
<li>First Category</li>
<li>Second Category</li>
<li>Third Category</li>
<li>Fourth Category</li>
<li>Fifth Category</li>
</ul>
and apply the following CSS:
.two-col-special {
border: 1px dotted blue;
overflow: auto;
margin: 0;
padding: 0;
}
.two-col-special li {
display: inline-block;
width: 45%;
margin: 0;
padding: 0;
vertical-align: top; /* In case multi-word categories form two lines */
}
.two-col-special li:before {
content: '+';
padding: 5px;
margin-right: 5px; /* you can tweak the gap */
color: orange;
background-color: white; /* in case you want a color... */
display: inline-block;
}
The trick is to change the display type to inline-block
and set a width to some number around 45%.
The plus sign is added as a pseudo element before the list item.
If you text (categories) are similar in length, then this will give you a reasonably clean look.
Demo fiddle: http://jsfiddle.net/audetwebdesign/4PdQw/