I think there are alot things involved in having a Dolphin site that would be considered 'successful'. You can build the best 'eye-catching', feature enhanced, website in the world. But it will not do you any good if you can't market it good enough and get the people to join. I hate bringing up Facebook, but honestly, how do you think it got all of those members? 1 person told another, another told 2, another told 5, etc.

I think that most members download this software and try to start the 'next see more big thing' in social networking. Oh really.. So you are going to get all these people to join your website and leave Facebook? Why should they? That is the key. You have to have some type of niche to your site that interests people. I have 20 domains registered (not all are running on the web yet) but I do plan on running Dolphin for the most part. My most successful website is aimed at Softball. Yep. I have over 400 members (real ones) on that site. I have 3 other Dolphin sites that have <50 members.

Another hard task to do, like you stated, is not only feel like you have to 'beg' people to join, but how about coming back once they do. Its possible to have a successful Dolphin site and the easiest way to do that is to not set your expectations too high. I would be ecstatic to have 50-100 members online at one time.