I came across Scalr by accident when I was browsing projects in Google Code. It appears as though Scalr has become a pay service to manage your AWS instances along similar lines to RightScale. But the main difference is that Scalr charges a scant $50 a month. From the Scalr Google Code page:
Scalr is a fully redundant, self-curing and self-scaling hosting environment utilizing Amazon’s EC2.
It allows you to create server farms through a web-based interface using prebuilt AMI’s for load balancers (pound or nginx), app servers (apache, others), databases (mysql master-slave, others), and a generic AMI to build on top of.
The health of the farm is continuously monitored and maintained. When the Load Average on a type of node goes above a configurable threshold a new node is inserted into the farm to spread the load and the cluster is reconfigured. When a node crashes a new machine of that type is inserted into the farm to replace it.
Multiple AMI’s are provided for load balancers, mysql databases, application servers, and a generic base image to customize. Scalr allows you to further customize each image, bundle the image and use that for future nodes that are inserted into the farm. You can make changes to one machine and use that for a specific type of node. New machines of this type will be brought online to meet current levels and the old machines are terminated one by one.
I would love to hear some comments from those already using the service and how it compares to RightScale.