Icon Joiner is a tool you can use to combine two sets of images to create one gigantic super-set of icons.
Let's say you have a set of shiny new icons. For each icon - a person, a clock, a document - you might want specific variants - add, delete, edit, save.
With Icon Joiner, you upload your three icons, and your four overlay images, and the tool combines them to produce a complete icon set!
It also produces a sprite of the images, and the associated CSS, so you can start using the new icons straight away!