I bought a few of these cheap ESP8266-12 modules from eBay. I'm pretty impressed so far with how easy it is to get a simple web server up and running.

Key learnings:

• The module has a number of IO pins which must have set state to run and another state to flash. GPIO0 needs to be tied low to flash.
• Needs hundreds of mA - can't run from USB->RS232 converter power.
• minicom (linux) doesn't send the required CRLF to the module. Have to manually use CTRL+M, CTRL+J
• Needs to be flashed with NodeMCU firmware to use LUA

python esptool.py --port /dev/ttyUSB0 write_flash 0x00000 ../Downloads/nodemcu_integer_0.9.6-dev_20150704.bin