doo - A smart, simple app for reminders and to-dos
Xmind - Xmind is a brainstorming and mind mapping application.
Purp - A smart to-do list and goal tracker app
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
Gone - An ephemeral to-do list
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.