One of the most fun things I've done with online image generators is to use them to make signs for posting on the inside of the back door at JAR. Keeping fresh, sometimes funny, signs that remind us to forward the phone, turn off the OPEN sign, etc. up for us to see as we're exiting at closing helps assure that we'll remember. . .
One of the favorites has been the Bart Simpson Chalk Board Generator (I will not forget to forward the phones. I will not forget to forward the phones. I will not forget. . .)