Simple Switcher PCB layout guidelines from Texas Instruments, app note here (PDF!)
One problem with writing an application report on PCB layout is that the people who read it are usually not the ones who are going to use it. Even if the designer has struggled through electromagnetic fields, EMC, EMI, board parasitics, transmission line effects, grounding, and so on, he will in all probability then go on with his primary design task, leaving the layout to the CAD/layout person. Unfortunately, especially when it comes to switching regulators, it is not enough to be concerned with just basic routing/connectivity and mechanical issues. Both the designer and the CAD person need to be aware that the design of a switching power converter is only as good as its layout. Which probably explains why a great many of customer calls received, concerning switcher applications, are ultimately traced to poor layout practices.
Sadly, these could and should have been avoided on the very first prototype board, saving time and money on all sides.