Some ideas and potential uses for this simple ESP8266 and ESP8285 based devices. Many have already been implemented and are available in Downloads.
Soil moisture sensors for managing plants.
Belkin WeMo Maker replacement (for about $10-$15).
Retrofitting (or re-programming) EZ buttons and various battery powered remote style switches
Wemos Mini shields as relay control (power, etc), indicators (using the built in LED or LED shield), "go" buttons, temperature, humidity
Garage door controller (open/monitor) using MppMaker (replaces the defunk belkin wemo maker)
Battery charger tenders for your android AM Server or carry phone (it can look after it for you using the rules engine).
Sonoff for wifi power switches, temperature & humidity sensors, power monitoring, etc
Splice a sonoff into an old extension cord as an automated control
Various digital sensors (e.g. HC-SR501 PIR motion sensor, $1.50 from ebay), door and window sensors (inexpensive security system reed switches work well)
Analog sensors using the MppAnalog type (may need additional programming to convert readings)
Adapt remote controls (e.g. RF or LED) for use over the internet, e.g. Wifi Door Lock, alarm system key fobs, garage door openers.
Manage your router and/or modem status Routers/Modems
Build your own garden watering/irrigation system accounting for rain, humidity, soil dampness, etc: DIGITEN 3/4" DC 12V Electric Solenoid Valve, driven with a 12V adapter plugged into a sonoff, scheduled handled by the AM Server. Multiple valves could be controlled with relays routing the 12V signal appropriately (again scheduled by the AM Server).