ESP8266 Projects
You can get a lot of great ideas from other people.
Not all of these contain an ESP8266, but they all triggered my interest in some way.
Wifi jammer/deauther
People point out that you can get into trouble with the law with one of these.
ESP as a remote microphone
Someone did this using a PIC in conjunction with an ESP8266, but I see no reason in the world why
this could not be done with the ESP8266 alone.