I'm writing a ruby program that need raw cpu power (I know ruby is a very bad choice for this!).. but I don't have a powerful computer, so I wanted to rent something online that you pay per hour..
Any idea? Something simple to use yet very powerful, with multiple cores. I took a look at amazon ec2, that's a possibility. Anything else, more CPU oriented?
As far as on-demand compute power, Amazon's EC2 is a good choice. You can either pay market rates or you can go to their special discount spot market which is similar, but your instance can and will be terminated without warning when demand picks up again.
It's best to have a system that either uses a persistent EBS drive to save results, or saves them to something like S3 frequently.
If you can parallelize your processing, try and split it across the most cost-effective instance type instead of having to pay a premium for a single instance. For example, the XL Hi-CPU On-Demand Instance gives you 20 compute units for $0.68/hr. compared with the 4XL Cluster Compute Instance which is only 33.5 for $1.60/hr.
Remember that a single Ruby process can only use one CPU core unless you're using a combination of JRuby and threads. You will need to support multiple processes in order to make full use of the machine if this is not the case.
SimpleWorker - I think it's more simpler then EC2.