Just finished the circuit design for my Lego clock, it features 4 ICs, an Arduin uno chip, uln2803 transistor array, operation amplifier and a PICAXE 14m2.  The Arduino controllers the main aspects of the clock, for example the servos which change the digits, the I2C communication with the RTC module, the remote control and the feedback from the LDRs.  Then the PICAXE 14M2 drives the RGB strip-light on command from the arduino uno chip.  The op-amp converts the analogue signal from the LDRs to a digital output for the arduino to handle as it doesn't have enough analog pins.  Finally the ULN2803 is used to power the strip light from the 12V in as well as switch on and off the background LED's and servos whilst the clock is not changing.  Definitely my most complex circuit board yet.