Idealist - Volunteer, work, and intern job search
Xmind - Xmind is a brainstorming and mind mapping application.
Idea Hunt - Solve specific challenges for your favorite products
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
Nugget - Find your perfect startup idea
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.