Through June 30, 2011, Delta is offering a 25% transfer bonus for transfers from Membership Rewards of up to 100,000 miles, and a 40% transfer bonus for transfers of 100,000 or more miles. Registration is required.
Now, for the time being this isn’t especially useful for most, given that Delta still has a 50% transfer bonus promotion valid through May 31, which also offers 25,000 Medallion Qualifying Miles when transferring at least 50,000 points. The catch is that the promotion is limited to the first transfer only, which is why the 25%-40% bonus might be useful for subsequent transfers. It’s worth keeping in mind, though, that if you’re not just looking to top off an account you can always use someone else’s account to transfer points to, taking full advantage of the 50% bonus and giving them Silver Medallion status along the way.
All of this assumes you would actually want to transfer Membership Rewards points to Delta, which is a huge assumption.
(Tip of the hat to TMtravelworld)