The answer is probably "my phone" - it seems that for many people the phone has become their primary alarm clock. We have discussed this before in a blog post…
Some years back I took part in a design competition at the appliance design conference and suggested an alarm clock that links you to your friends . One of the ideas was to have dynamic wake up times based on when you friends got up. The paper was accepted in March 2005 - this was before twitter was founded and before facebook was open for general registration. At this time we envisioned this as a stand-alone appliance as micro-blogging was not yet around.
Time has move on and many appliance ideas have since become apps on the phone. In the course of his research Ali is working on ideas for increasing the connectedness between people. One of the case studies is now an alarm clock - called weSleep - that has the basic alarm clock function and has additionally means to log sleep hours and perceived sleep quality. It also allows to post information related to the going to sleep or being woken up to social networking software such as facebook.
Interesting in trying it out? Check out the web page of weSleep and if you are interested in taking part in a study please contact Ali (not sure if he still is interested in more volunteers).
 Schmidt, A. 2006. Network alarm clock (The 3AD International Design Competition). Personal Ubiquitous Comput. 10, 2-3 (Jan. 2006), 191-192. DOI=http://dx.doi.org/10.1007/s00779-005-0022-y