Thanks for the reply. A few questions.

Why do you not want to sign in with gmail? I had imagined a gmail password-less signup. There would be only one field: your email ID. The login would then cling on to your computer, unless you want to use the website from another computer in which case, you can enter your emailID again, and you're back.

I think an easy sign in is the most easy way to avoid ghost towns. The way I'm avoiding the ghost town effect is by asserting that this is not a social website. The next time you want to have a discussion with bob and harry, you could just add their emailIDs to the discussion, or paste the discussion link on them. They would click on it, click 2 more buttons to sign in, and voila: They're in the discussion in a flash. The next time they visit, they will have their dashboard with the previous discussions they made.

The point is, you don't need thousands of users to be in town, to enjoy this town. Only when I have MANY users, will I then roll out a public discussion feed. Till then, its only micro-site tool to help you talk with the people you know in a better way.

I don't want to use gmail because i don't want to have a global online identity. But it depends on what you see as the primary use case (corporate? technical? casual?). Optional gmail is fine. If it's all private then maybe i'd be OK with it, but it doesn't seem like this is your long-term goal. I'm not certain how the security would work with what you are describing, i guess it requires you to be signed in to gmail constantly, but password-less option sounds good. Friction must be extremely low. Outside of gmail, make sign up just username /password.. avoid the sign-up email if you can. Think about if you really need someones email.

You will of course have to make this 100% perfect and have a lot of great ideas (but those can grow organically later) to get very far with this, IMO, but i wish you luck.

Not gmail - because I don't have one.