Older computers make GREAT local NAS solutions. For file storage the memory and processor requirements are not that intense. This works really well for engineering or other groups with more localized and larger data volume requirements. The only downside is it WILL become one more computer that will need to be worked into a regular backup schedule.
Another note, older computers also make for GREAT Apache / Linux web servers. Depending on the requirement and how robust the hardware is you can even use them for web production purposes (or development as you mentioned). The nice thing about the Apache web development is that other than production specific sizing it can generally mirror production environments.
Bill Wood - President
R3Now Consulting
Navigating IT. High Performance Now!
http://www.R3now.com 
