A friend shared this app with me... cloudywithachanceofpain.com
I've had a look and it seems really interesting, and I thought people here might be interested too... Anyone with chronic pain can use it and take part in University of Manchester research at the same time. It asks questions about your pain and daily activities, and links your reports with local weather. Eventually, it will report on whether there is actually a link between weather and pain, as so many people believe. It also has handy note/diary functions and you can set alerts for your meds. If you're inquisitive, it lets you access some of the data set too, and explore it to form your own hypotheses about the correlates of pain...
(PS. Hope this doesn't break the research rules... I'm reporting my own post so an admin can check!)