This morning I left some slightly negative feedback about a purchase on the Amazon website (the packaging overkill issue I blogged recently).
Within a minute (literally) of clicking submit the company that fulfilled the order called me to address the issue.
One of the most critical parts of delivering good customer service is to actually listen to your customers; that's the only way to learn about problems so you can fix them, and it has the added benefit of making your customers feel valued.
You'd be amazed how many companies don't get that (like the hotel I blogged about yesterday, who haven't bothered to respond to the email I sent them).
Onecall.com clearly get it. I'll happily order from them again knowing that if there's a problem they'll be on it faster than Usain Bolt.