Here is the link
"Between October 1 - 31, 2008, whenever you transfer miles to a friend or family member on delta.com, your recipient will receive a 100% mileage bonus. For example, if you transfer 10,000 miles, your recipient would get 10,000 bonus miles."
If you transfer 30K from your account to ur friend/family accounts, they will get 60K in total, then they transfer those 30K back to you, you will get 60K, so basically you are"buying miles" at 0.01 cent each+ $30 processing fee.
Up to 30,000 miles can be transferred per transaction, A maximum of 300,000 miles can be transferred into any individual SkyMiles account per calendar year. Up to 150,000 miles can be transferred from your account per calendar year.