Mockup files are everywhere, from the latest phones, to billboards. As well as being great for presentation purposes, they are a quick and easy solution to see whether the design actually looks good within the intended surrounding.
Here I have created a simple 2013 iMac Mockup in the form of a PSD file, and with the help of smart objects you can easily replace the image of the screen to be whatever you like with a few clicks. The style is as simple as it is effective, and will take no limelight away from your creations. The download is completely free for both commercial and personal purposes. Enjoy.