Request for Startup - Share and discover great startup ideas people actually want
Idealist - Volunteer, work, and intern job search
#RequestForProduct - A crowdsourced directory of product ideas people wish exist.
OpenVC - 2200+ VC firms by thesis to find 'best fit' for your startup
Infinideas - Infinite feed of crowdsourced ideas from the web
Idea Hunt - Solve specific challenges for your favorite products