Don't count on the HIPPA thing -- not only a lot of things that used to be illegal are now happening, but there are all kinds of loopholes in laws. If I remember right, HIPPA prohibits releasing *your* or *mine* or *their* medical information, but it does not prohibit enough things from happening. I'd be surprised, for example, if it has anything to say about aggregates, randomized info and anonymous info, for example. So, they could gather medical info from say, one million browsers, aggregate them and remove "personal identifying info" from the data and sell it.
So, what's the problem, you ask? It's an aggregate and all personal info has been stripped, right?
Yes. And no.
If you have diabetes in NYC, LA, SF, Boston etc, you are probably safe.
If you have a rare form of cancer and live in Santa Barbara, CA, they might have your data. If you live in a place whose population is less than 10,000 and the "aggregate" offers as little as neighborhood or street name, they may have your file.
The entire problem is more complex than people would intuitively grasp.
For example, there used to be (maybe you can still google and find them) websites that used to offer you an idea of how "unique" your browser is. Things like what machine, OS, fonts browser, memory size etc could all be sniffed and a "unique index" (your system appears to be one in 10 million, for example) would show up even if you were coming thru VPN or TOR (I have not been keeping tabs on that, I don't know if they fixed that "flaw" in TOR), another more recent way to correlate your system with the one using TOR is sniffing the delay the mouse movements ("mouse sniffing") show at the other end, not sure if they corrected that yet or not.
So, maybe they don't know that "Joe Q. Public" who lives in Beverly, MA, USA has such and such medical problems. But if they buy enough browser data from different places, they might find out that a user whose browser/mouse uniqueness is 1 in 50 million lives in Beverly, MA, USA and has this list of medical issues, and data from other websites say that Joe Q. Public lives in Beverly, MA, USA (easy to get from their ISP) and maybe just those two websites, or maybe a third or forth website will correlate the name, the address and the "unique browser".
The good news is that in places where health insurance companies cannot deny coverage for "pre-existing" conditions or, even better, charge people more for having diseases, the privacy of medical data becomes nearly irrelevant.
Cheers,
-- Paulo.