I don't know if you guys have ever heard of quickmats, but it is basically a photoshop plugin that will make quality, realistic mats for your images. It is good for presentation and enables you to preview what your image might look like matted. However, I looked into it, and it is 200 dollars. So I decided to try my hand at making a mat in photoshop, I think it turned out decently. I've separated all the corners and all the sides so that you can move each piece for differently cropped pictures. I've also added two layers on top that can adjust the color of each layer of mat. Just select the contents of each layer and fill with your desired color. It really is quite simple. The initial frame size is 2500x1667 (3x2)
Here is an example image using the mat I made, click on it for a bigger version.