Nuggets of info you've found here

I learn something everyday i get on this forum.
What are some of the nuggets and gems you have found on here, big or small?
The other day I read how to prolong my microwave by not opening the door while it is in operation and how to fix it if it does stop working. Might be a smaller nugget of truth, but this kind of knowledge does help everyday life.
A much bigger nugget I have learned from this site is that people/buyers on this forum pay much more for circuit boards than scrap yards do. So glad I found this site before I sold any of my high grade boards to the local scrap yard.
The list of nuggets could go on for miles and days: how to make money on ink cartridges, what kind of light bulbs have gold plating, rare earth magnets, buyers for all types of material even material that looks like dirt or trash to most people, ect...
Thanks to all you contributing members. Please keep sharing the knowledge.