Sent to you by Chris Hunter via Google Reader:
While I think it's safe to assume that the average Lifehacker reader knows their Wi-Fi password off the top of their head, the same can probably not be said for most of our friends and family members.
When you visit with someone a little less tech-savvy, make a point to find their Wi-Fi password and write it on a piece of masking tape. Just stick the tape to the back or the bottom of their router, and they'll always have it nearby if they need to share if with a house guest or service technician. This will also come in handy if you're trying to remotely diagnose their connection issues over the phone.
Of course, if this is your own router we're talking about, it's much cooler to use a QR code for easy password sharing.
A Quick and Easy Wi-Fi Password Reminder Solution | Apartment Therapy