The best option for running background (cron) jobs in the cloud.
NodeChef is both faster and cheaper than DIY. NodeChef provides a managed service with montioring included. There is no need to buy, configure and continue to manage servers and purchase additional monitoring for your cron jobs. NodeChef provides all this functionality in a straight forward easy to use service.
The number of concurrent jobs you can run is constrained by the available RAM on your container.
Buying multiple containers ensures your jobs are highly available, if a host running your container goes down, your jobs should run on the other container which is always provisioned on a different host.