We added a new, free PCB CAD package to our list: Solo PCB Design. It has no design limits imposed upon it, but it can only be used with a specific manufacturer. Currently, that manufacturer is Mass Design, but the software developer, FabStream, says that seven more manufacturers will be added soon.
Unfortunately, you must download the version of Solo tailored to one specific manufacturer. Also, it appears that if you create your design in one manufacturer’s version of Solo PCB Design, you can not open it in another manufacturer’s version of Solo PCB Design (according to the FAQs).