Dell Ideastorm - This is a kind of Digg, basically to generate and rate ideas for new Dell products.
Online Brainstorming - A good and interesting site. Submit your Ideas for whole world to brainstorm on it. Brainchild of an Indian entrepreuner - Anand Chhatpar.
Change - This is a site where people share which things in public life, they want to change. The suggested changes are also presented in a cloud of change-ideas. I went for 'Improve Public Schools', and found that 152 people had voted for this change. There are some community blogs on this subject and also opinions of people as why they want this change.
aniBOOM (Youtube for animations) - Need I say more? This site has filled up a void of social sharing service, exclusively devoted to user generated animations.
Check this one from aniBOOM! This is my favorite.