Until June 21, 2017, there is a 25% transfer bonus from American Express Membership Rewards to Hawaiian Miles.

Transfers of American Express Membership Rewards to Virgin Atlantic miles will have a 30% bonus through May 22, 2017.

This is a fantastic deal that sets up a chance to book one way awards to Europe for 8,000 Membership Rewards+ $150.

You must transfer Membership Rewards in 1,000 point increments, so until May 22:

1,000 Membership Rewards = 1,300 Virgin Atlantic miles

Three Reasons Why You Want Virgin Atlantic Miles
1.

Through April 30, 2017, transfers from hotel partners to Etihad Guest will earn a 20% bonus.

Your best transfer options are probably between Starwood Preferred Guest and Etihad, or purchasing a Marriott Hotel + Air Travel Package that contains Etihad miles.

Normally, 20,000 SPG points = 25,000 Etihad miles (thanks to the everyday 5k bonus you get on transferring in increments of 20k), so with the current transfer bonus, 20,000 SPG points = 30,000 Etihad miles.
As One Mile at a Time pointed out, normally for Marriott Hotel + Air Package 2, you'd pay 270,000

Transfers of Citi ThankYou Points to JetBlue TrueBlue points will have a 50% bonus through 11:59 PM ET April 30, 2017.

This could be a very good deal if you have

Transfers of Citi ThankYou Points to Virgin Atlantic miles will have a 25% bonus through tonight, 11:59 PM ET March 2, 2017.

This is a fantastic deal that sets up a chance to book one way awards to Europe for 8,000 ThankYou Points + $152.60.

You must transfer ThankYou Points in 1,000 point increments, so until March 2:

1,000 ThankYou Points = 1,250 Virgin Atlantic miles

Getting ThankYou Points

Citi Prestige Card: 50,000 bonus ThankYou Points after $4,000 in purchases made with your card in the first 3 months the account is open.

Virgin Atlantic is dramatically altering its award charts for bookings made January 16, 2017 or later.

The United States goes from two regions to three.
The year round price is no more. Now we will have off peak and peak prices.
Economy and Premium Economy prices for most of the year drop dramatically.

Through November 31, 2016, United MileagePlus is offering a transfer bonus when you move points over from a hotel loyalty program.

Transfer from most chain hotels earn a 25% bonus
Transfers from Club Carlson earn a 40% bonus
Transfers from Choice Privileges earn a 50% bonus

Since Marriott bought Starwood, one of the benefits the company has announced to members of both loyalty programs is the ability to transfer reward points between accounts.

250 Membership Rewards will transfer to 300 British Airways Avios from now until 11:59 p.m. CT on October 10, 2016. The normal transfer rate is 250 Membership Rewards = 200 British Airways Avios, so this transfer bonus will get you 50% more Avios.

For only 25,000 Avios and $11, you can fly roundtrip on American Airlines or Alaska Airlines planes in economy from the West Coast to Hawaii.

You have less than two weeks left to take advantage of this transfer bonus! 

Until September 14, 2016, you can transfer 20,000 SPG Starpoints to 30,000 American Airlines AAdvantage miles.

Right now 40k Starpoints plus taxes will get you a roundtrip economy class trip to Europe, 80k Starpoints will get you a roundtrip Business Class ticket, and 95k will get you a roundtrip First Class ticket.

Starpoints always transfer to dozens of airlines at a 1:1 rate with a bonus of 5,000 miles for every 20,000 Starpoints transferred.