TweetDeck - TweetDeck is your personal browser for staying in touch with what’s happening now.
GnuPG - GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
Tweetbot - Sync your timeline across your iPhone, iPad, and Mac. Mute tweets by user, hashtag, tweet source, or keywords (including regex). 3rd Party support for image, video, read later, and timeline sync services.
Kleopatra - Kleopatra is a certificate manager and GUI for GnuPG.
HootSuite - Enhance your social media management with Hootsuite, the leading social media dashboard. Manage multiple networks and profiles and measure your campaign results.
PGP Tool - PGPTool allows you to encrypt and decrypt files. It's free and easy to use.