This is possibly the coolest idea for a website that I've seen in a long time. I think the reason is that it's more than a website, it's a real service, that will really help people, and it's completely free!! It's called MediClim, and its purpose is to monitor changing weather patterns where you live, and alert you to triggers for the health issues you have!
Here's the link to the weather health warning system, Mediclim.
Apparently the system monitors weather on 14 different indices. It can correlate them currently to five different conditions: asthma, heart disease, migraines, diabetes and arthritis. And I guess they'll continue adding more as the research provides more data.
Let me know what you think of it!