Edit : looks like Retro-Man answered faster.
Many way of using Daemon tools especially with the new version.
To sum up, it allows you to use a CD image (Iso, Bin+cue, nrg (nero)) as it was a real CD.
First test the ISOs/Cue+bin you got. Instead of wasting one or more CD, you can run the images from the hard drive.
Then you can make a compilation of CDs. A game like The terminator : Future Shock only uses 98 Mb. So instead of using a whole CD, you can burn the Cue+bin image with other stuff on a cd. Then you'll select the cue file in dameon tools and your image will behave like the real CD would.
This might be useful when DVD-burner will be cheap.
And finally now that analogic audio has been implemented, you can run Dracula X : Rondo of Blood on Magic Engine.
The full image was unburnable (many people reported this) and ISO+mp3 just isn't fatihful enough.
So now you just have to run the image from your hard drive or a CD.