It all depends on the target audience though doesn't it. For example my website is aimed at a 50 mile square radius of my country, we don't advertise anywhere and is just spread by word of mouth - the target audience is lovers of alternative and rock music... There aren't that many living here. We've had about 5000 registrations and currently have about 1000 active members since inception in 2001. Getting a load of members on launch is great... You just have to make sure they stay!