Recently LoneWolfPack Interactive released their first tool on the Unity Asset Store, LTexturePacker.
A brief video of the features is right here:
Along with exporting the atlas, LTexturePacker exports an XML with the information that you’ll need to use in your project.
With the XML file, LTexturePacker also exports an enumerator with the sprite names that can be used with a utility class that comes with the tool to apply the texture sprite to your object with two lines of code.
You can grab LTexture Packer here for $5.00