focalist:
You know, that might make a very useful thread.. "I made this mistake, watch out for it!".. things that people tend to forget or not think of that end up being "gotchas".
And entertaining besides 
Re LM317, even without a heatsink, if fastened a PCB with a machine screw, be sure the copper is sufficiently relieved around the hole (if a ground plane) or appropriately isolated, don't count on solder mask for insulation.
I had a list of "rules", will have to see if I can find it. The only one I remember is: "Beware the lightening that lurketh in the undischarged capacitor, lest it cause thee to bounce upon thy buttocks in a most ungentlemanly like manner."