I've Had Just One User Since May 2010
Back in January of 2010 I failed my annual physical exam. My blood pressure was measured at 168 over 80. Apparently this is high. I was told by my doctor to get a blood pressure machine and start taking my blood pressure every day in the hopes that it would report that my blood pressure is normal and that I tested high at my physical exam because of anxiety. OK. To skip to the end of the story, yes, my blood pressure is normal, at most times, but tends to be high when measured by medical professionals. 

I hate paper lists, so I wrote a quick little web app so I could record my blood pressure on a daily basis and keep track of the resulting average.  Because I am who I am, I registered recordmybloodpressure.com and exposed my little application to the world.

In May of 2010, user number 653 recorded his/her first blood pressure and pulse readings. User 653 has entered data every day since.