My mate Alon Nativ just referred me to JetBrains newly introduced TeamCity feature: integration of their Continues Integration (CI) platform with Amazon EC2. This new feature enables on demand instances during the CI process.
CI tends to have non linear usage behavior: Minor use in the beginning of the project, and massive use in the end of the day and just before releasing the new version.
During these peak hours TeamCity can launch on demand instances, running the build and the tests and shut down the instances when it ends.
It is a fine example of how development teams can keep their infrastructure costs as low as possible, while maintaining maximum flexibility.