Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.

Advowire - Advowire is a great crowdsourcing software for social media influencers!

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

Influenster - Influenster is your source for honest product reviews. Discover new products, read beauty news, watch tutorials, and shop and share your favorite products.

Bigtent - BigTent is a web-based organization and communication portal for groups.

Pollseye - < 30 seconds video reviews of products ("user-generated QVC")