I use a Windows program called "Eagle" made by
CadSoft Online. This is a great schematic to PCB design program to use. And best of all, it's FREE (some restrictions apply). The learning curve is a little steep, but after a few hours of practice, it becomes intuitive and you begin to appreciate it's power and capability.
The Autorouter feature is great. Basically, the program will find the best possible path to connect your components together. Or, you can do it manually but the program still helps you by guiding you when connecting the points together.
Once you're done with your PCB design, you can send it off for manufacturing or prototyping.
UPDATE!!!! Eagle software can now run on Mac OSX! Woohoo!!! Caveat is, it's run under X11. But doesn't matter... because the files that I saved on the PC worked just fine when opened on the Mac OSX (X11) version.
Here's some screenshots.
The Eagle control panel running under OSX (X11)
The Board editor
