EXPERTS - How Would You Launch A Social Media Site?

Hello all

I was hoping that the social super warriors here can assist me.

We all get great ideas every now and then, but it's the rare few that take action.
I'm a person who takes action the moment I come up with something that is truly worth the risk, time and effort.

I'm a born affiliate marketer. I'm damn good at what I do, but I today I got a pretty amazing idea for a social media site and I'm thinking I HAVE to jump at this opportunity asap. The only problem is I'm struggling to put together a battle plan for launching such a service.

The social media site is geared towards my country and I'm 1000% sure that it will get a lot of response if it gets enough exposure.

Social media is big...and if you are going to launch a social media site it needs to make an impact right from it's launch.

That's where I am stuck.

Every now and then I see blog aggregation services, social dating sites and content driven social sites launch with big impacts. I mean, they launch the stuff so quickly and with a bang!!

How can I go from setting up a social media site to launching it without it being a ghost town right from the start??

Most of the variables will be in place except for one.

1. Awesome idea
2. Awesome site
3. It opens to the public
4. ?????? - now what?

Do any of you have a strategic approach to launch a social media site so that I don't have to rely on spending thousands to advertise such a free site? I mean, social media sites don't rely on heavy advertising. It's all word of mouth right? (I might be wrong that's why I'm asking)

Is there any methods I can use to get the word out as quick as possible?

Regards
Reinhardt