Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Profile Hopper - Chrome Extension to Growth Hack LinkedIn
TechEvents.co - Tech and startup events aggregator
LeadBring - Automate your LinkedIn workflow
Facebook Local - Discover places to go and events happening near you
Marketing for Startups - 47 practical tactics to get customers and achieve hockey stick growth.