Arduino +Sparkfuns 4-digit 7-segment 16pin display

Don't have one, but looks easy enough. Connect the common anode digits contacts through transistors to individual arduino pins. Connect the seven segments (A - G) and the decimal contact through resistors to arduino pins. If you want to use the colon and/or apostrophe, connect the cathode through a resistor to +5 and the anode to an arduino pin.

Takes a bunch of pins of course. You could use shift registers if you want.

Look in the forum for threads on driving seven segment displays. You are multiplexing (one digit at a time). You drive a digit pin high (which drives the anode low). You drive the segment pins high to light a segment. You pause, drive the anode pin low, and move on to the next digit. You might use 100hz, so each digit is on for 2.5ms

If you use the colon/apostrophe, drive it during one of the digits, so it has the same on time as a digit.