But most of my customers used RDS and are now on MySql, MariaDb, or PostgreSql. Similarly, S3 -> CEPH. Nginx as front-end, Varnish as cache, Ha-Proxy for load balancing. Queues? RabbitMQ. Map-Reduce? Hadoop. Lots of data? ZFS.
There are A LOT of great open source projects to base your infrastructure on.
