Avenir in action on influential.co

• .header-1 { font-family: Avenir-Book, "Avenir Book", "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif; font-size: 30px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-transform: none; color: #464D5D; }
• .content-1 { font-family: Avenir-Book, "Avenir Book", "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif; font-size: 16px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-transform: none; color: #464D5D; }
• .content-2 { font-family: Avenir-Heavy, "Avenir Heavy", "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif; font-size: 16px; font-style: normal; font-weight: normal; letter-spacing: normal; line-height: 28px; text-transform: none; color: #464D5D; }

Avenir is available from Fonts.com and MyFonts.