I've sold on www.roadbikereview.com. I was contacted by a local buyer and everything worked out. As a buyer I follow the local craigslist. For bikes and other high-dollar transactions I'm wary of spending money (or shipping goods) on an ebay transaction where I don't know the other party, although I know a lot of people who are comfortable with it. I guess that the bottom line for me is that local is more safe, even though as a seller there are ways to protect your self with ebay. If you don't live in an area with a healthy local used bike market, ebay might be the best market for your sale. I'm sure others will disagree ...

try the classifieds here and at trinewbies.com and slowtwitch.com and RBR as noted above

I bought a used bike from trinewbies.com paid by paypal and he boxed and shipped to me from Texas (we actually used greyhound to ship it) I reassembled the bike and have been happy ever since.

I bought my most recent addition on Ebay..
It was a local purchase, so we met up in the city and exchanged bike/money no problems..