Immediately after hiring
I really like what Jordon has done with Cloudsponge and CodeIgniter and how he explained it here: http://www.hiretheworld.com/blog/tech-blog/importing-contacts-with-cloudsponge-in-codeigniter
There is a nice buddypress plugin http://wordpress.org/extend/plugins/invite-anyone/ that can also work with CloudSponge.
I would like to use Cloudsponge with buddypress/wordpress and create invite your friends referral system like Jordon did. Pretty much it would work in a way that users would earn cash by inviting friends. Best way to see what i have in mind is to checkout: http://www.thefancy.com/find_friends You have to sign up with thefancy to see what i have in mind. And just invite someone by email so you could get $1 and see how it is applied.
So for example for 1 invited friend you would get $1 to spend in the store (It would be a woocommerce store such as http://demo2.woothemes.com/smpl/) Then $1 or whatever amount would be automatically applied in woocommerce shopping cart during checkout.
We would like to use the same concept for invite your friends referral system as the fancy uses.
Please note if you have other system in mind other than cloudsponge for buddypress i would be also willing to consider it.