我建议 vertical-align: middle 应用您的图标字形.例如:

h3 .fa {垂直对齐:中间；}

http://jsfiddle.net/22cYh/

I'm trying to vertically center text in a div, but I can't get it working.

The code:

<div>
    <h3><i class="fa fa-cloud fa fa-3x"></i> Text</h3>
</div>

Does anyone have a solution for this? I tried many possibilities but none of them seem to work.

I would suggest vertical-align: middle applied your icon glyph. For example:

h3 .fa {
    vertical-align: middle;
}

http://jsfiddle.net/22cYh/