https://www.eff.org/pages/how-deploy-https-correctly seems to be an
informative and well written article that may be of interest to the web
developers on the site.  I cannot attest to its accuracy, but it looks like
it probably is.

I can relate one good anecdotal story related to this.  I once wanted to buy
something from a web site.  When I got to where they were asking for
personal info and credit card info, I saw the page was not secure so I
backed off and did not purchase the item.  There was also an email address
listed so I went to my email client and typed in the email address (not
using the link on the web site) and wrote to him stating my reason for not
purchasing.  He wrote me back and said that had I clicked the button, the
information would have been sent securely and that he was trying to minimize
his bandwidth costs since he was a small company.  I asked him to consider
whether the lost sales might cost him more than the extra bandwith and he
reprogrammed the site to use https beginning with any request to purchase.
BTW, I ordered from him by mail.

-- 
Dazed_75 a.k.a. Larry

The spirit of resistance to government is so valuable on certain occasions,
that I wish it always to be kept alive.
  - Thomas Jefferson