I've got my head around creating cloud instances in AWS, Azure and Rackspace. However, I need to turn my instances off at the end of the day and on in the morning as this will half my hosting cost (they are for development).
I've looked at a few management services but they blew my brains out. Is there a simple way to do this?
You could always roll your own solution, insofar most cloud providers offer a respective API to start/stop instances on demand (or even on schedule), which is what those management services are actually using as well of course - the AmazonEC2 Java interface offers all relevant methods for example (amongst many others), specifically:
The most simple approach for this regarding Amazon EC2 would be to craft yourself some Python scripts by means of the excellent boto (An integrated interface to current and future infrastructural services offered by Amazon Web Services), which exposes all EC2 methods mentioned above; you could then start those scripts on demand or via your operating system scheduler.
Another option would be to facilitate a continuous integration server as an automation engine (a sometimes overlooked aspect of these systems), in case you happen to run one anyway; it would allow you to both start/stop instances on demand or scheduled similar to cron.
We do exactly this by means of the Bamboo AWS Plugin (it's Open Source and the code is available on Bitbucket), see my answer to How to start and stop an Amazon EC2 instance programmatically in java for more details on this approach. While Atlassian Bamboo is a commercial offering, there should be something similar available for popular Open Source CI solutions like e.g. Jenkins as well.