Virtualization -- IT's best friend
I remember years ago whenever I wanted to play with a new server OS, it always required me to have a separate physical machine to run it on. This was a major drawback and made it difficult to experiment with designing server infrastructures consisting of multiple servers and tiers(clustering, load balancing, etc,.). If I wanted to load balance an Apache server and see the effects it had on the running application, it was difficult to emulate a bunch of Apache nodes running behind a load balancer because I only had access to one or two physical machines....