I think it's a tough problem to solve. In the beginning stages of your product, unless it goes viral, you'll be desperate and thankful for any users you can get, although you'd prefer 'normal' users (i'll call them "normies").
The problem with getting normies is that they're incredibly hard to reach. Outside of the tech sphere, few normies have heard of Quora, hacker news, digg, even reddit. Think what % have heard of any other number of less known startups. The answer is probably less than 1% for normies. They don't seek out new experiences online; they'll sign up only if your site goes super-viral, as facebook and twitter did. I think the problem is inherent in Normie behavior - they simply don't have much time to invest in or thought to give to new online startups.
The solution, I believe, is to target a niche community - either local or with a group of people who already socialize with each other. This is a purely an area of execution strategy and is quite fraught with difficulties, imo.