I recently viewed the @coinbase onboarding process and noticed a very nice “invite friends” link easily and readily viewable in the top nav.  This is a great idea and one I think a lot of sites are not doing but should!

FireShot Capture 1 - Referrals - Coinbase - https___www.coinbase.com_invite_friends.png

My Thoughts:

One additional thing would be to add video and provide ideas of how you could share with friends.  #coinbase provides the gmail, share, tweet buttons but they also need to help people with ideas of how to share.  Providing some videos of ideas or a articles/ebook would be great!  Also adding text messaging would be critical, it’s the fastest way to hear and be heard!