It's a great question. One is protection from ISPs. Over http, they can see everything you're browsing -- the exact page and data -- whereas with https I believ

It's a great question. One is protection from ISPs. Over http, they can see everything you're browsing -- the exact page and data -- whereas with https I believe they only see the top-level domain (e.g. they know you're on hacker news, but not which thread). Worse, the ISP can potentially modify pages, inject code and advertisements, etc. In the US, we know that ISPs have done these things and now sell browsing info to advertisers. This was enough to convince me to add https to my static blog.