I had a couple of requests from people that they'd like an audible alert if someone arrives at the table where they're seated. In response to this, I've added a "shop bell" sound when someone arrives, and a "door shutting" sound when someone leaves.
I don't plan on adding any more sounds, since I don't want the site to get too noisy. Remember, if you don't like the sounds, there's an option to turn them off in your user profile area (click on your user name up in the top right corner to see this).