e-Net work

• Elftown
• Ello
• Elixio
• English, baby!
• Epernicus
• Eons.com
• eToro
• Experience Project
• Exploroo 

• Fetlife
• FilmAffinity
• Filmow
• FledgeWing
• Flickr
• Flixster
• Focus.com*
• Fotki
• Fotolog
• Foursquare
• Friendica
•  Friends Reunited
• Friendster
• Fuelmyblog
• Fyuse

*I love Wikipedia, as you can tell, but again check for accuracy. They have a separate post for defunct social media yet here is Focus.com now defunct, as is: