Stealthy: Secret Messenger - Chat anonymously with friends & strangers
Xmind - Xmind is a brainstorming and mind mapping application.
Berkanan - Chat with people nearby. Even offline, on an ✈️.
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
Treadie - Create your own micro-social network for topics
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.