Fun idea, though I don't think I'd trust it with anything important, as obviously it requires trusting the website owners were and are sincere and uncompromised, and all the code they include.
If you're concerned about giving at least the impression of privacy though, your pages should not contain third party, and externally hosted js -
Given the number of sites this sort of js is included on, it must be a huge target now for people interested in breaking into websites and stealing info. If even one of the smaller social networks like stumbleupon was hacked you could take over and keylog quite a few sites just by adding something to the js, then once you have admin access, you have the site.
If you're concerned about giving at least the impression of privacy though, your pages should not contain third party, and externally hosted js -
https://platform.twitter.com/widgets.js
https://platform.stumbleupon.com/1/widgets.js
Given the number of sites this sort of js is included on, it must be a huge target now for people interested in breaking into websites and stealing info. If even one of the smaller social networks like stumbleupon was hacked you could take over and keylog quite a few sites just by adding something to the js, then once you have admin access, you have the site.