invisible data storage

I'm far more involved in customizing, maintaining, and learning more about my software than most people, but I got a glimpse of the casual user's experience today when I briefly thought firefox was doing more than I knew it could.
I had to reinstall my operating system a couple of times in the past few months, so I expect most of my browsing history to be missing - but when was searching for some PHP programming help, I saw a purple link that I was sure I hadn't visited in over a year. While I remembered fairly quickly that I had visited it more recently, I was thrilled by the thought that FF had backed up my history online.
Now ordinarily I'd be pissed that they were invading my privacy this way (in fact I generally download and store on my own hard drive most of the gmail/gdocs/calendar data I wouldn't want to become part of the public record) - but for this functionality I would be thrilled for Mozilla to track my browsing history and help me either find or avoid the sources I've used before, depending on my intent.
I think the primary difference is that I have a model for my personal data in calendars, documents, and email. I've had those totally under my control, and I know all the details of what it looks like and what's in it. But with browsing history, I have no concept of the database structure, the kinds of details that are involved (and which are left out), nor how/when/where I would use that data in any other context. I think this is what keeps me from being upset about it: it doesn't really seem like *my* data, and almost not like anything at all - thus if Mozilla can turn it into any sort of insight at all for me, I feel like I'm getting that for free!