As I stated in my previous posts, I am now running my sites on one Amazon EC2 Micro instance and one Micro RDS.
It is 14 days into the months now, and the cost of the RDS is more expensive than EC2.
The RDS is currently $8.35
The EC2 is currently $6.89
The data usage is only 20¢
Running the RDS and EC2 is great for sites that get alot of traffic and are content/media heavy. My sites are neither, just a bunch of smaller niche sites. I will be working on setting up an new EC2 with MySql built in and migrating to that.