Earlier this month, Google mentioned that you can now insert "images into a cell". With the image() formula you can link to a publicly accessible image and control how it'll look with optional parameters. This is useful for bringing a visual element to your spreadsheets for things such as a product catalog listing.
For e.g. the formula: =image("http://www.google.com/intl/en_ALL/images/srpr/logo1w.png", 1) will scale the image down in the current cell. With other parameters you can choose from a variety of sizing options including size to fit, stretch, original size, and even specify a custom size.
Try them all out using this template.