Sparkun are selling the following simple clock on their site: Link
ClockIT from Sparkfun
This is a minimalistic clock that includes all the essential functions and is very similar to a product offered at Maplins in the UK that I have used before: Maplin link | My project which includes this module
There are two differences between the two clocks from Sparkfun and the Maplin. The first one is that the Sparkfun clock runs at 5V; the Maplin clock needs 9-18V (which then regulates down to 5 and generates quite a bit of useless heat in the process…). This for me, is a major design flaw! When I used it for this project, I had to power it from a USB port, which basically meant that I removed the voltage regulator and changed the wiring a bit to accommodate for the lower voltage.
The second difference is that the Sparkfun clock is based around the ATmega168 chip (i.e. the old Arduino chip). It would be nice if the code (provided by Sparkfun on their website) was in the Processing/Arduino language.
These are great modules to use for custom applications. Of course you can go down the I2C real clock module path and use something like this. The problem is that you add a whole new layer of complexity to your module. You need a way to display the time, controls to adjust the time, etc, etc… If you just need a basic alarm clock to flip a switch at a specific pre-defined time, just get one of these modules, replace the speaker with a transistor and you are sorted…
Anyway, enough about alarms 
