Alluminare is a site that lets you be the designer (with a little help of some great pre-designed templates).
You can choose to have your design on wallpaper, lampshades, fabric and cushions - so everything co-ordinates beautifully and it's custom designed!
It work like this:
Choose the item you'd like to design - I chose wallpaper for this exercise.
The next screen let's you purchase that product but click 'change' to get to the custom design screen.
Now choose your new style of design on the left from a great range - modern, paisely, stripes etc.
Within each category are further choices of individual designs (middle of the page). You can keep changing them until you find what you're looking for so just have fun.
Every colour in the design is variable and the choices are neatly categorised into easy colour groupings like Blues, Neutrals, Grays etc.
Scale your design up or down if necessary and order your new wallpaper!
This is also a great tool to play around with if you're experimenting with colour palettes.