Because my projects most of the time are relatively small I am using cheap pcb circuit boards from chinese suppliers. But since in the last few months I am working on a project that maybe it will go commercial I had to do some proper pcb designing in order to send my designs for pcb printing. The best web based tool I found to do so is the EasyEDA. Really simple to use with big component library. If you are a beginner or you need something quick and easy for small pcbs give it a try here.