Product review (5 stars): Saved hundreds of dollars
After my friends whom I regularly visit had been having increasingly worse intermittent dryer problems (lack of heat), I decided to try and fix it for them.  Initially, I figured the heating element had broken, as I found that to be the case when my dryer stopped heating after a move once.  But if the heat is intermittent, you should definitely check out the relay first.  Located behind the control panel, once you get to this thing it is easy to replace.  Just make sure the dryer is unplugged, of course.

Picked this up and replaced it for them, and the dryer has been working perfectly ever since.