I just tried it today and I have to say I'm amazed. It can mount any compressed archive, so that you don't have to extract the files in order to use them.
Makes it much easier and saves much space, when you can access those files inside the multiple RARs without having to wait for them to be extracted. Especially those multiGB games, and even the latest episode of your favorite TV show.
[ i5 2500K (@4.2GHz) / GIGABYTE Z77MX-D3H / 8GB Corsair XMS / GIGABYTE GTX460 1GB OC / 640+750 GB WD Caviar Black ]