Another one is putting someone on hold when you already know the answer as if you need to check with someone else to get approval. That tends to put some friction that prevents to much time from being wasted. Another use is if someone wants a discount. If you agree to quickly they can think it was to easy and might wonder if there is money on the table.
Do this many times in negotiation as well typically. Even if you know you will sell (or buy) at a certain price you can't agree to quickly.
(Once again all this depends on your product, who you are selling to and what you are trying to achieve.)
I learned recently that some companies will offer to waive accrued finance charges to get you off the phone, as part of the robo-system before the human agents answer.
I assume that in this case, they can afford to do so because the finance charges were fraudulent in the first place (Hello, GAP)
I think the key question here is whether or not your job is just to provide simple data, such as answering routine questions or some such, or developing a relationship with somebody. Many companies get so enamored with systematizing their process that they lose track of the big picture (in my opinion)
I was reading somewhere that when you call the guys at Zappos, they're there for as long as you want to talk to them. They'll even go online with you searching competitor's websites if they don't have what you need.
I like the robot idea, though. Need to try that one out!