I got two "Purchase Checks" with my Capital One statement. These are not those cash advance checks you get all the time from credit card companies. These "checks are treated as purchases and will post to your Purchase segment." They don't earn miles, but they don't accrue interest either. Since the deadline for use is June 30, I could write one out now for deposit to my bank for just under half of my credit limit, wait until the closing date for the current month's transactions, then write out the other for just under half of my credit limit. The second will pay off the first that way as long as I make sure the money is in my bank account on the due date for my automatic payment, and then I'll need to pay off the second a month later, but having had free use of the money for quite a few weeks.

I could simply put the money in an investment account and hope for the best, but does anyone have any nice mileage tactics, any way to use these funds to earn mileage during the weeks I have them, but still be able to have the monies available again when the payments come due? Of course, if they send me more purchase checks in future months, I could just keep rolling the funds over. I assume others are getting these purchase checks, and know a lot more than me about how to maximize their use.