1Blocker - 1Blocker is a content blocking software that you can rely on to save time and money. Unlike its competitors who use JavaScript to block ads after they have been download, 1Blocker does the contrary. Read more about 1Blocker.
PixelBlock - Block email open tracking inside of Gmail
Ugly Email for FireFox - Get back your email privacy, block email tracking
sendso - sendso enables you to send something to anyone using just their email address.
Email Privacy Protector - Check the presence of email ids on your webpages using Email Privacy Checker tool and protect yourself from email spammers.
Ghostery - Privacy tool for transparency and control