Right now, cloud monitoring entities are very "cloud server"-centric. A common situation is a cloud application which runs on several servers, each of which collects the same metrics. It would be nice to easily combine these metrics into one "virtual entity" for monitoring. The virtual entity would contain metrics which are aggregates of metrics on other entities. A few functions like average, median, sum, and min/max would probably suffice but obviously there are many more possibilities.

Obviously it is possible to do this in the application which consumes the monitoring data but it seems cleaner to keep this in the monitoring layer if possible.

I strongly recommend that you allow for email notifications on a per-server basis for your cloud monitoring If you had that feature you could definitely sell a lot more monitoring since your customers who use Rackspace for web hosting could pass on the cost and better serve their customers. Our customers often ask to be personally notified by email if there is a problem with their server. At present we cannot provide that service as it would be too time consuming. For this reason the way server monitoring works now (only one email address for all servers) makes it impractical for us to use.