One of the investors behind Google, PayPal, Twitter, and Facebook, Silicon Valley angel investor Ron Conway has spread his wings to the East Coast, backing about 10 Big Apple start-ups, including Foursquare, Stack Overflow, and BankSimple. Since his first Internet investment in 1994, Conway has provided seed money and critical introductions to many companies that make the web hum. The investment he regrets not making? Salesforce.com, according to one report. Now good friends with Salesforce.com CEO Marc Benioff, the top executive at the cloud CRM provider frequently brings up the blown opportunity, Conway told the The Wall Street Journal.