My First Sitecore Marketplace Module has just been released! You can check it out here Icon Selector Field.
It allows content editors to select CSS font icons via a custom field that include a SPEAK UI Dialog for searching and selecting icons.
The field also show a preview of the icon when it has been set in the CMS.
If you are using Glass Mapper the Module also includes an AbstractSitecoreFieldMapper for this field so you can add CustomIconField types to your models and access with @Model.Datasource.Icon.CssClass.
You can have a look at the code on GitHub and there will be a post to come detailing the implementation.