Phantom CD

Phantom CD is a small and useful application that lets you mount ISO, CUE and VDD image files from CD/DVD/Blu-ray discs to a virtual drive in your computer.

It basically lets you read an image file as if it were an actual disc present on your system.
What is interesting about this program is the possibility to avoid physical discs along with problems associated with them (scratches, dirt, slower reading speeds, etc.), but you will need a good storage size to make the most of this program, since an ISO file is usually large.
If your hard disk space is big enough, you can start building a collection of image files (with different applications like nero, roxio, etc., since Phantom CD can't create image files) and mount them with the help of this free tool. Advantages include an easier organization of your discs (you can store them in folders inside your hard drive instead of trying to deal with a bunch of CDs), and faster reading (up to 200 times faster because you don't depend on your optical drive). This program is free so you can download it at no cost.