Placehold.it is one of the many time saving tools for designers/developers when it comes to generate placeholder images. It allows you to create placeholder images with customizable dimensions, color, format(jpeg,png,gif) and include text too.
Inorder to create an image, all you need is a the link from Placehold.it – which is customizable.
For e.g., if you need a dummy image with width 300px and height 500px, you need to define in the link – http://placehold.it/300×500
Again, If you need an image with color #666666, which is 300×500 in size and has font with color #FFFFFF and text Hello World then the link will be:
More details about this is available in the website.
This amazing tool is provided free by Brent