The steampunk concept of building devices to resemble items from the 19th century is a fun and interesting challenge, and one fine example of this has been demonstrated by Instructables member gfish with their clock in a top hat.
Time is kept with an Arduino-based system, which drives two servos to control the hands of the clock. In the steampunk fashion, over-sized gears are used between the servos and hands to create an external display mechanism that works. Furthermore a time-zone selection panel is included - and a GPS-based location mode that displays relative postition to a certain area using the clock hands. A full demonstration is shown in the following video:
The most important part of any clock or timer-based project is the inclusion of an accurate real-time clock IC. Here at Freetronics we have the Maxim DS3232 real-time clock IC module:
Apart from keeping accurate time for years due to the temperature-controlled oscillator and having a tiny coin-cell for backup, it is very simple to connect to your Arduino project. A driver library allows your program to easily set or read the time and date. Perfect for clock projects, dataloggers or anything that needs to know the date and time. Furthermore it contains a digital thermometer and 236 bytes of non-volatile memory to store user settings and other data. For more information, check out the module page here.