Sorry, a little late here ...
Brands of the World is always a good place to check in a pinch. Case in point: This will get you started. It's the standard jQuery mark. From there, you just have to rebuild the rectangles for the mobile version, which is a pretty simple task.
It's best to just ask the organization for the artwork. If you have a legitimate use most companies will appreciate the extra publicity. Of course, they'll probably want to see the final use before it goes to print. That's only fair since you're presumably using their name to add value to your product.