I absolultely agree, it's so important to keep in touch with your references. A lot of times, people will blindly list people, just to have names to write down. The problem is, your references may not remember you or worse yet, no longer be at the company.
In fact, we just tried to contact references for a potential hire, and the references's phone number was DISCONNECTED! So what does that say about the candidate? In the recruiting world, quite a bit!