Timezone is the most common watch site. Another one that is dedicated to Rolex is called TURF - The Ultimate Rolex Forum. A few years ago when I was selling a new in box stainless steel Daytona I used the guy who runs TURF to sell it. He's a real NYC watch merchant. He'll do everything he says he will, exactly the way he says he will. If you ask the question, he will answer it. If you don't ask it, he won't volunteer an answer. But he's a good guy to use to sell the watch to outright, or to use to sell it on consignment. People buying used watches sometimes pay more to buy a consignment watch from a dealer they know than they would over the internet to the person who actually owns the watch.
TURF has a small community and is very similar in look and feel and member participation to PP, both in a tech forum and an off topic forum. If you post on there, a dozen pros and semi pros will walk you through the sale, tell you all the pitfalls, and the site has a page called "good guys" and another one called "bad guys" where people report their sales experience.
Check it out. It's my second favorite site behind PPBBS
http://www.newturfers.com/