What good live chat/live help solutions are available (preferably for use on a site hosted on a LAMP stack and free)? I'm looking for a way to allow our sales and customer service reps to talk directly with visitors to our site.

I've looked at phpopenchat, but it looks very unpolished. The only other free live chat app I've come across looked egregious. The aesthetics and UI design alone made me shudder to think what the underlying code might look like.

This isn't a critical feature, and it wouldn't be hard to code up myself, so I'm not really looking for commercial software or paid services (unless there's a really compelling reason to use them). I'm just wondering if any other webmasters have come across a satisfactory free/open source solution for providing live customer support on their website.

As a side note, live voice chat would also be an option, but it has to be be designed (or customizable) for customer support rather than a public chatroom.

Edit:

Looking at the responses, it looks like there probably aren't going to be many free solutions for this type of business-oriented chat solution, so feel free to post answers even if they are commercial solutions as long as they're a good value.

Also feel free to post any alternate live support solutions (such as the Skype recommendation) that could be in someway integrated with a website.

This will give me a good lay of the land for what people are actually using for live support, and I think will be more helpful to others reading this question.