At our company LimoenGroen we use Drupal on a daily base. To improve the quality of our development process, we implemented a continuous integration workflow based on Jenkins.
Continuous Integration builds, updates & tests the full website automatically after every change in the code, which results in increasing the overall quality of the development process.
We presented our CI setup a few times before during several Drupal meet-ups and shared the slides. On our company blog we now share a bit more in-depth information on how we've set it up and how you could achieve the same.
For more information, I highly recommend reading the full post Continuous Integration & Drupal at LimoenGroen.