The web server firmware opens up a ton of possibilities with CGI scripting. When booting up in AP mode, you can even connect the ESP8266 to another access point right from the your browser.

Arduino has a library for quickly and easily setting up a simple web server on an ESP8622-based board, and [Tomaž] found that power consumption on an ESP-01 can be reduced a considerable amount ...

Using MicroPython on the ESP8266 will allow you to create beautiful Internet of Things devices with ease, much quicker than with C or similar compiled languages, and using Python is a lot of fun!