Imikimi is a popular website that lets you create all types of retouches to your photos, and also add fun, attractive and surprising effects and filters to alter them as you wish. For comparison, it's similar to websites like Photofunia. To use Imikimi you just need to register for free on the author's website and download this plugin.
This plugin adds a toolbar to your web browser from which you can manage all your Imikimi account, and start to make (or modify) your designs and creations. It is an ideal program to create all types of postcards, animations, wedding invitations, birthday cards, surprise gifts for loved ones, etc.
Once the design is finished, Imikimi lets you print it out (with professional results), send it via email to a contact or even publish it directly on a website like Hi5.