PartyTalk - An efficient, fee-free event planning & ticketing tool
Ideas Grab - A list of +3400 ideas that you can get for your projects.
XCalSync - Automatically copy events between your calendars.
The 25 Days of Ideas - Free resources for coming up with startup ideas
Repartee - Social event planning rethought for the mobile era
Validated ideas - List of 5,000 poorly executed but popular apps