We have seen great sales from what we are calling the "Takeover Week"
We basically ask an existing customer to send us 5 photo's and some details about themselves over to us.
We post these photos with the information about them (and with links to any sites/profiles/blogs they have, so it's win win ) and then encourage them to share with their friends.
They usually do this and then all of their friends "like" and see these amazing leggings and feel a need to keep up with their social group, hence buying the leggings
Thought I would share as is really working for us at the moment. This can be used for any e-commerce site I would imagine.
Let me know if you have any feedback/improvements/suggestions!