This is a reminder that the 15% bonus Delta Skymiles you get when you transfer Membership Reward Points into Delta Skymiles will expire on 31st July 2010. If you are looking to get a free airline ticket with Delta Skymiles and are short of some miles, you might just want to check your Membership Reward points to see if you have enough to transfer over to get that free flight. Remember, the 15% bonus deal ends this Saturday.