Here is one:
http://www.createforless.com/EK+Rule...pid156450.aspx
Its an EK Rulers Pro 3"x 15" Acrylic
You might find others at Craft for Less, just type in rulers in the search tool at the top. This online store sells more than just quilting supplies and this ruler is really a scrapbook ruler, but hey, it works just as well for quilting.