Points.com is a site where you can manage all your loyalty programs in one spot, move points and miles between programs and have access to promotional offers. You can also redeem points and miles via the site for shopping and gift cards. It is free to join.
You can see which loyalty partners Points.com partners with, here.
As with any other redemption and exchange offers, make sure the offer is worth it to you before you close on the transaction. Think about where these points will be the most valuable based on your future travel plans.
I have never used this site. I will let you know if and when I do.