Virtual CloneDrive is a very powerful free utility from slysoft.com. Virtual CloneDrive allows you to mount .ISO, .CCD, .DVD, .IMG, .UDF and .BIN files. Personally I liked it very much and found it better then the famous Daemon Tools.
After installing, you can select a ISO file, right click and mount or un-mount. It is so easy to use. I personally like it so much.
Download Virtual CloneDrive from slysoft.com
Remember to download Virtual CloneDrive as they also have other tools like CloneDrive etc. Only Virtual CloneDrive is free other tools are not free.