I got a couple of new module types recently and have started to experiment with them. On the left is the ESP-03, and on the right is the ESP-07. Both modules have 2mm pin spacing, so are not breadboard friendly.

I built a breakout board for the ESP-03. it brings out the pins to 0.1" pitch headers and also adds a 3.3V LDO

Although several sources list this module as having a RESET pin, it is not broken out to the headers. Is is available on a small pad near the antenna. I wired this to the NC pin next to GND.

I also chose not to breakout the external WiFi antenna pin at this stage.

The ESP-07 modules look very interesting. They have all the pins I need to make an wireless sensor board, including:

• RESET and GPIO16 - to allow deep sleep mode
• ADC pin - to monitor battery voltage
• Other GPIOs to connect sensors.