1Password - 1Password can create strong, unique passwords for you, remember them, and restore them, all directly in your web browser.
Stealthy: Secret Messenger - Chat anonymously with friends & strangers
ClockTweets - Schedule, analyze, and stalk challengers on Twitter
Phonebot - Make phone calls from within a Slack channel
LessNoise - Recommendations on who to unfollow on Twitter
Vuash - Send secret messages safely.