438 Facebook, Inc. Palo Alto, California

222 Twitter San Francisco, CA

45 Boxee

16 Foursquare

12 Zynga San Francisco, CA

10 comScore Inc. SCOR 18.20 (+0.22%)

7 Tumblr New York, NY

3 Disqus San Francisco, CA

2 Activision Blizzard, Inc. ATVI 11.09 (+0.73%)

1 Etsy Brooklyn, NY

1 Meetup New York, NY

1 Outside.in Brooklyn, NY

1 Union Square Ventures New York, New York

1 Zemanta

AMEE San Francisco, CA

Alacra New York, New York

Bug Labs

Clickable

Covestor New York, NY

Indeed

InfoNgen New York, NY

Oddcast New York, NY

Return Path, Inc. New York New York, New York

Simulmedia New York, NY

TargetSpot New York, NY

Tracked.com New York, NY

Wesabe San Francisco, CA

heyZap

iBiquity Digital Corporation

10 Evan Williams Twitter

4 Dennis Crowley Foursquare

1 David Karp Tumblr

1 Dick Costolo Twitter

1 Howard Lindzon StockTwits

1 Mark Pincus Zynga

1 Matt Blumberg Return Path, Inc. New York

1 Reid Hoffman LinkedIn Corporation

1 Scott Heiferman Meetup

1 Zach Klein Boxee

Albert Wenger Union Square Ventures

Bijan Sabet Spark Capital

Brad Burnham Union Square Ventures

Brad Feld Foundry Group LLC

Daniel Ha Disqus

Dave Morgan Simulmedia

David S. Kidder Clickable

Gian Fulgoni comScore Inc.

Isaak Karaev InfoNgen

Jack Dorsey Square, Inc.

Magid M Abraham comScore Inc.

Marc Andreessen Ning, Inc.

Maria C. Thomas None

Mark Josephson Outside.in

Michael Yavonditte Tracked.com

Robert Kalin Etsy

Steven Johnson Outside.in