I like the oversized foam stamps which are intended for printing on t-shirts. When I couldn't find any themed for Christmas I decided to find an alternative way to make my own. I cruised the Christmas craft section and bought various shapes for other projects and then used heavy duty glue to adhere each to a free sample piece of flooring (available at your local super-sized building supply store). I used a 6"x6" Gelli Art printing plate as my "stamp pad" and "inked it up" with a liberal dose of acrylic paint from a tube.
There are several variations on the theme. You can simply use the Gelli Art plate like an ink pad, inking and re-inking (washing between as appropriate) or you can use the Gelli Art plate as the stamp. Of course a combination also works. I worked on a journal page which already had some basic preparation done for the background. I chose purple to provide a strong impact image and to complement the existing colors.