Many MCU applications use electro-mechanical relays to control AC loads. While this is an excellent solution for occasionally turning on/off a load it is not suited for frequent switching or PWM applications. SSR01 is an opto-coupled solid state relay that can control two AC loads up to 16A each.
USTK01 is a small USB device that allows the connection of thermocouples (using MAX6675 or MAX 31855), humidity sensors (DHT11/DHT22) or any I2C or RS232 device (5V or 3.3V).
Despite the significant advantages in size, weight and efficiency, switching AC-DC supplies are not very common with hobbyist due to their complexity and scarcity of ready to build kits.
PWR01 is a low power (~6W) universal voltage (100-240V) isolated AC-DC flyback converter based on the ST Microelectronics VIPer17. Either 5V or 12V output can be obtained using an off the shelf transformer.
Linear regulators from the 7800 series are often the choice for electronics hobbyists because of their ease of use, versatility, robustness and availability. G78xxHE is a very small DC-DC converter aimed to be a "drop in" replacement for the 7800 series regulators in TO-220 package. Thanks to its high efficiency the G78xxHE does not need to be connected to an heatsink even when delivering the maximum rated 7800 series current (1A) with large Vin-Vout deltas.
The Maxim MAX6675 and the newer MAX31855 thermocouple to SPI interface chips are very popular with electronics enthusiasts because of their extreme ease of use combined with good accuracy.
Both devices however are only available in SMD package making breadboard prototyping very difficult without using a suitable breakout PCB. Standard thermocouple connectors are also not breadboard friendly further aggravating the issue.
The freescale S08JS series is one of the lowest cost microcontrollers with a hardware USB implementation. The availability of free C development tools (SDCC and Codewarrior) make the S08JS a great candidate to develop all sorts of inexpensive USB gadgets. microJS is a fully functional S08JS minimal system on a PCB less than a square inch. The board headers can be plugged into a breadboard for prototyping or soldered to another PCB for a permanent placement.