The 5050 RGB LEDs with WS2812B driver chip are a 4 pin version 5mm x 5mm in size. These programmable RGB LEDs are surface mount and can produce 16.7 million colours. Weighing in at just 0.16g each.
These LEDs are 'chainable' by connecting the output of one chip into the input of another. To allow the entire chip to be integrated into a 6-pin package, there is a single data line with a very timing-specific protocol. Since the protocol is very sensitive to timing, it requires a real-time microconroller such as an AVR, Arduino, PIC or mbed and cannot be used with a Linux-based microcomputer or interpreted microcontroller such as the netduino.
Note: These LEDs come in units of 10 on a tape. Multiple orders will come in a continuous strip of tape.